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See A/C Performance in the Diagnosis and Testing section of this group for the procedures. If the A/C system refrigerant fill is found to be low or if the sys- tem is empty; a leak at a refrigerant line, connector fitting, component, or component seal is likely.
An electronic leak detector designed for R-134a refrigerant, or a fluorescent R-134a leak detection dye and a black light are recommended for locating and confirming refrigerant system leaks. Refer to the operating instructions supplied by the equipment manufacturer for the proper care and use of this equipment.
An oily residue on or near refrigerant system lines, connector fittings, components, or component seals can indicate the general location of a possible refrig- erant leak. However, the exact leak location should be confirmed with an electronic leak detector prior to component repair or replacement.
To detect a leak in the refrigerant system with an electronic leak detector, perform one of the following procedures:
SYSTEM EMPTY
(1) Evacuate the refrigerant system (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING/RE- FRIGERANT - STANDARD PROCEDURE).
(2) Connect and dispense 0.283 kilograms (0.625
pounds or 10 ounces) of R-134a refrigerant into the evacuated refrigerant system (Refer to 24 - HEAT-PLUMBING
24 - 51
ING & AIR CONDITIONING/PLUMBING/REFRIG- ERANT - STANDARD PROCEDURE).
(3) Position the vehicle in a wind-free work area.
This will aid in detecting small leaks.
(4) With the engine not running, use a electronic R-134a leak detector and search for leaks. Because R-134a refrigerant is heavier than air, the leak detec- tor probe should be moved slowly along the bottom side of all refrigerant lines, connector fittings and components.
(5) To inspect the evaporator coil for leaks, insert the electronic leak detector probe into the center instrument panel outlet and the floor duct outlet. Set the blower motor switch to the lowest speed position, and the mode control switch in the recirculation mode (Max-A/C).
SYSTEM LOW
(1) Position the vehicle in a wind-free work area.
This will aid in detecting small leaks.
(2) Bring the refrigerant system up to operating temperature and pressure. This is done by allowing the engine to run with the air conditioning system turned on for five minutes.
(3) With the engine not running, use a electronic R-134a leak detector and search for leaks. Because R-134a refrigerant is heavier than air, the leak detec- tor probe should be moved slowly along the bottom side of all refrigerant lines, connector fittings and components.
(4) To inspect the evaporator coil for leaks, insert the electronic leak detector probe into the center instrument panel outlet and the floor duct outlet. Set the blower motor switch to the lowest speed position, and the mode control switch in the recirculation mode (Max-A/C).
STANDARD PROCEDURE
STANDARD PROCEDURE - REFRIGERANT SYSTEM EVACUATE
WARNING: (Refer to 24 - HEATING & AIR CONDI- TIONING/PLUMBING - WARNING) AND (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - CAU- TION) BEFORE PERFORMING THE FOLLOWING OPERATION.
If the refrigerant system has been open to the atmosphere, it must be evacuated before the system can be charged. If moisture and air enters the system and becomes mixed with the refrigerant, the com- pressor head pressure will rise above acceptable operating levels. This will reduce the performance of the air conditioner and could damage the compressor. Evacuating the refrigerant system will remove the
PLUMBING
24 - 52
REFRIGERANT (Continued)DR
air and boil the moisture out of the system at near room temperature. To evacuate the refrigerant sys- tem, use the following procedure:
(1) Connect a R-134a refrigerant recovery/recy- cling/charging station that meets SAE Standard J2210 and a manifold gauge set (if required) to the refrigerant system of the vehicle and recover refrig- erant.
(2) Open the low and high side valves and start the charging station vacuum pump. When the suc- tion gauge reads 88 kPa (26 in. Hg.) vacuum or greater, close all of the valves and turn off the vac- uum pump.
(a) If the refrigerant system fails to reach the specified vacuum, the system has a leak that must be corrected. See Refrigerant System Leaks in the Diagnosis and Testing section of this group for the procedures.
(b) If the refrigerant system maintains the spec- ified vacuum for five minutes, restart the vacuum pump, open the suction and discharge valves and evacuate the system for an additional ten minutes. (3) Close all of the valves, and turn off the charg-
ing station vacuum pump.
(4) The refrigerant system is now ready to be charged with R-134a refrigerant(Refer to 24 - HEAT- ING & AIR CONDITIONING/PLUMBING/REFRIG- ERANT - STANDARD PROCEDURE).
STANDARD PROCEDURE- REFRIGERANT RECOVERY
WARNING: (Refer to 24 - HEATING & AIR CONDI- TIONING/PLUMBING - WARNING) AND (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - CAU- TION) BEFORE PERFORMING THE FOLLOWING OPERATION.
A R-134a refrigerant recovery/recycling/charging station that meets SAE Standard J2210 must be used to recover the refrigerant from an R-134a refrig- erant system. Refer to the operating instructions sup- plied by the equipment manufacturer for the proper care and use of this equipment.
STANDARD PROCEDURE- REFRIGERANT SYSTEM CHARGE
WARNING: (Refer to 24 - HEATING & AIR CONDI- TIONING/PLUMBING - WARNING) AND (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - CAU- TION) BEFORE PERFORMING THE FOLLOWING OPERATION.
After the refrigerant system has been tested for leaks and evacuated, a refrigerant charge can be
injected into the system. See Refrigerant Charge Capacity in the Service Procedures section of this group for the proper amount of the refrigerant charge, this fill level can also be found on a label attached under the hood of the vehicle..
A R-134a refrigerant recovery/recycling/charging station that meets SAE Standard J2210 must be used to charge the refrigerant system with R-134a refrigerant. Refer to the operating instructions sup- plied by the equipment manufacturer for the proper care and use of this equipment.
this vehicle is:
The R-134a refrigerant system charge capacity for † If equipped with a 3.7L or a 4.7L engine charge † If equipped with a 5.9L engine charge to 0.7371
to 0.6804 Kg. (24 oz.).
Kg. ( 26 oz.).
REFRIGERANT LINE COUPLER DESCRIPTION
Spring-lock type refrigerant line couplers are used to connect many of the refrigerant lines and other components to the refrigerant system. These couplers require a special tool for disengaging the two coupler halves.
OPERATION
The spring-lock coupler is held together by a garter spring inside a circular cage on the male half of the fitting (Fig. 16). When the two coupler halves are connected, the flared end of the female fitting slips behind the garter spring inside the cage on the male fitting. The garter spring and cage prevent the flared end of the female fitting from pulling out of the cage. Three O-rings on the male half of the fitting are used to seal the connection. These O-rings are com- patible with R-134a refrigerant and must be replaced with O-rings made of the same material.
Secondary clips are installed over the two con- nected coupler halves at the factory for added blowoff protection.
REMOVAL
WARNING: (Refer to 24 - HEATING & AIR CONDI- TIONING/PLUMBING - WARNING) (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - CAU- TION) BEFORE PERFORMING THE FOLLOWING OPERATION.
(1) Recover the refrigerant from the refrigerant system(Refer to 24 - HEATING & AIR CONDITION- ING/PLUMBING/REFRIGERANT STANDARD PROCEDURE).
DR REFRIGERANT LINE COUPLER (Continued)
PLUMBING
24 - 53
Once the garter spring is expanded and while still pushing the disconnect tool into the open side of the coupler cage, pull on the refrigerant line attached to the female half of the coupler fitting until the flange on the female fitting is separated from the garter spring and cage on the male fitting within the dis- connect tool.
NOTE: The garter spring may not release if the A/C line disconnect tool is cocked while pushing it into the coupler cage opening.
Fig.16Spring-LockCoupler-Typical
1 - MALE HALF SPRING-LOCK COUPLER 2 - FEMALE HALF SPRING-LOCK COUPLER 3 - SECONDARY CLIP 4 - CONNECTION INDICATOR RING 5 - COUPLER CAGE 6 - GARTER SPRING 7 - COUPLER CAGE 8 - “O” RINGS
(2) Remove the secondary clip from the spring-lock
coupler.
(3) Fit the proper size A/C line disconnect tool (Special Tool Kit 7193 or equivalent) over the spring- lock coupler cage (Fig. 17).
Fig.17RefrigerantLineSpring-LockCoupler
Disconnect
(4) Close the two halves of the A/C line disconnect
tool around the spring-lock coupler.
(5) Push the A/C line disconnect tool into the open side of the coupler cage to expand the garter spring.
(6) Open and remove the A/C line disconnect tool
from the disconnected spring-lock coupler.
(7) Complete the separation of the two halves of the coupler fitting. Inspect the O-ring seals and mat- ing areas for damage.
INSTALLATION
WARNING: (Refer to 24 - HEATING & AIR CONDI- TIONING/PLUMBING - WARNING) AND (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - CAU- TION) BEFORE PERFORMING THE FOLLOWING OPERATION.
(1) Check to ensure that
the garter spring is located within the cage of the male coupler fitting, and that the garter spring is not damaged.
(a) If the garter spring is missing, install a new spring by pushing it into the coupler cage opening. (b) If the garter spring is damaged, remove it from the coupler cage with a small wire hook (DO NOT use a screwdriver) and install a new garter spring. (2) Clean any dirt or foreign material from both
halves of the coupler fitting.
(3) Install new O-rings on the male half of the cou-
pler fitting.
CAUTION: Use only the specified O-rings as they are made of a special material for the R-134a sys- tem. The use of any other O-rings may allow the connection to leak intermittently during vehicle operation.
(4) Lubricate the male fitting and O-rings, and the inside of the female fitting with clean R-134a refrig- erant oil. Use only refrigerant oil of the type recom- mended for the compressor in the vehicle.
(5) Fit the female half of the coupler fitting over
the male half of the fitting.
(6) Push together firmly on the two halves of the coupler fitting until the garter spring in the cage on the male half of the fitting snaps over the flanged end on the female half of the fitting.
PLUMBING
24 - 54
REFRIGERANT LINE COUPLER (Continued)DR
(7) Ensure that the spring-lock coupler is fully engaged by trying to separate the two coupler halves. This is done by pulling the refrigerant lines on either side of the coupler away from each other.
(8) Reinstall the secondary clip over the spring-
lock coupler cage.
REFRIGERANT OIL DESCRIPTION
The refrigerant oil used in R-134a refrigerant sys- tems is a synthetic-based, PolyAlkylene Glycol (PAG), wax-free lubricant. Mineral-based R-12 refrigerant oils are not compatible with PAG oils, and should never be introduced to an R-134a refrigerant system. There are different PAG oils available, and each contains a different additive package. The SD–7 com- pressor used in this vehicle is designed to use an SP-15 PAG refrigerant oil. Use only refrigerant oil of this same type to service the refrigerant system.
OPERATION
After performing any refrigerant recovery or recy- cling operation, always replenish the refrigerant sys- tem with the same amount of the recommended refrigerant oil as was removed. Too little refrigerant oil can cause compressor damage, and too much can reduce air conditioning system performance.
PAG refrigerant oil is much more hygroscopic than mineral oil, and will absorb any moisture it comes into contact with, even moisture in the air. The PAG oil container should always be kept tightly capped until it is ready to be used. After use, recap the oil container immediately to prevent moisture contami- nation.
STANDARD PROCEDURE - REFRIGERANT OIL LEVEL
When an air conditioning system is assembled at the factory, all components except the compressor are refrigerant oil free. After the refrigerant system has
been charged and operated, the refrigerant oil in the compressor is dispersed throughout the refrigerant system. The accumulator, evaporator, condenser, and compressor will each retain a significant amount of the needed refrigerant oil.
It is important to have the correct amount of oil in the refrigerant system. This ensures proper lubrica- tion of the compressor. Too little oil will result in damage to the compressor. Too much oil will reduce the cooling capacity of the air conditioning system.
It will not be necessary to check the oil level in the compressor or to add oil, unless there has been an oil loss. An oil loss may occur due to a rupture or leak from a refrigerant line, a connector fitting, a compo- nent, or a component seal. If a leak occurs, add 30
milliliters (1 fluid ounce) of refrigerant oil to the refrigerant system after the repair has been made. Refrigerant oil loss will be evident at the leak point by the presence of a wet, shiny surface around the leak.Refrigerant oil must be added when a accumulator, evaporator coil or condenser are replaced. See the Refrigerant Oil Capacities chart. When a compressor is replaced, the refrigerant oil must be drained from the old compressor and measured. Drain all of the refrigerant oil from the new compressor, then fill the new compressor with the same amount of refrigerant oil that was drained out of the old compressor.
Refrigerant Oil Capacities
Component
Complete A/C System
Accumulator Condenser Evaporator
Compressor
fl oz
ml 180
60
30
60drain and measure the oil from the old compressor - see text.
DR
EMISSIONS CONTROL
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EMISSIONS CONTROL
TABLE OF CONTENTS
page
page
EMISSIONS CONTROL
DESCRIPTION
DESCRIPTION - STATE DISPLAY TEST
DESCRIPTION - MONITORED SYSTEMS . . . . 1
DESCRIPTION - TRIP DEFINITION . . . . . . . . . 4
. . 4
DESCRIPTION - COMPONENT MONITORSMODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
OPERATION
DESCRIPTION - CIRCUIT ACTUATION TEST
MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
DESCRIPTION - DIAGNOSTIC TROUBLE
CODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
DESCRIPTION - TASK MANAGER . . . . . . . . . . 1OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . 4
OPERATION - TASK MANAGER . . . . . . . . . . . 5
OPERATION - NON-MONITORED CIRCUITS . . 8
. . . . . . . . . . . . . . . . 10EVAPORATIVE EMISSIONS
EMISSIONS CONTROL
DESCRIPTION
DESCRIPTION - STATE DISPLAY TEST MODE
The switch inputs to the Powertrain Control Mod- ule (PCM) have two recognized states; HIGH and LOW. For this reason, the PCM cannot recognize the difference between a selected switch position versus an open circuit, a short circuit, or a defective switch. If the State Display screen shows the change from HIGH to LOW or LOW to HIGH, assume the entire switch circuit to the PCM functions properly. Connect the DRB scan tool to the data link connector and access the state display screen. Then access either State Display Inputs and Outputs or State Display Sensors.
DESCRIPTION - CIRCUIT ACTUATION TEST MODE
The Circuit Actuation Test Mode checks for proper operation of output circuits or devices the Powertrain Control Module (PCM) may not internally recognize. The PCM attempts to activate these outputs and allow an observer to verify proper operation. Most of the tests provide an audible or visual indication of device operation (click of relay contacts, fuel spray, etc.). Except for intermittent conditions, if a device functions properly during testing, assume the device, its associated wiring, and driver circuit work cor- rectly. Connect the DRB scan tool to the data link connector and access the Actuators screen.
A Diagnostic Trouble Code (DTC)
DESCRIPTION - DIAGNOSTIC TROUBLE CODES indicates the PCM has recognized an abnormal condition in the system.
Remember that DTC’s are the results of a sys- tem or circuit failure, but do not directly iden- tify the failed component or components.
BULB CHECK
Each time the ignition key is turned to the ON position, the malfunction indicator (check engine) lamp on the instrument panel should illuminate for approximately 2 seconds then go out. This is done for a bulb check.
OBTAINING DTC’S USING DRB SCAN TOOL
(1) Obtain the applicable Powertrain Diagnostic
Manual.
(2) Obtain the DRB Scan Tool. (3) Connect the DRB Scan Tool to the data link (diagnostic) connector. This connector is located in the passenger compartment; at the lower edge of instrument panel; near the steering column.
(4) Turn the ignition switch on and access the
“Read Fault” screen.
(5) Record all the DTC’s and “freeze frame” infor-
mation shown on the DRB scan tool.
(6) To erase DTC’s, use the “Erase Trouble Code” data screen on the DRB scan tool. Do not erase any DTC’s until problems have been investigated and repairs have been performed.
DESCRIPTION - TASK MANAGER
The PCM is responsible for efficiently coordinating the operation of all the emissions-related compo- nents. The PCM is also responsible for determining if the diagnostic systems are operating properly. The software designed to carry out these responsibilities is call the ’Task Manager’.
DESCRIPTION - MONITORED SYSTEMS
There are new electronic circuit monitors that check fuel, emission, engine and ignition perfor-
EMISSIONS CONTROL
25 - 2
EMISSIONS CONTROL (Continued)mance. These monitors use information from various sensor circuits to indicate the overall operation of the fuel, engine, ignition and emission systems and thus the emissions performance of the vehicle.
The fuel, engine,
ignition and emission systems monitors do not indicate a specific component prob- lem. They do indicate that there is an implied prob- lem within one of the systems and that a specific problem must be diagnosed.
If any of these monitors detect a problem affecting vehicle emissions, the Malfunction Indicator Lamp (MIL) will be illuminated. These monitors generate Diagnostic Trouble Codes that can be displayed with the MIL or a scan tool. The following is a list of the system monitors: † Misfire Monitor † Fuel System Monitor † Oxygen Sensor Monitor † Oxygen Sensor Heater Monitor † Catalyst Monitor † Leak Detection Pump Monitor (if equipped) All these system monitors require two consecutive
trips with the malfunction present to set a fault.
Refer to the appropriate Powertrain Diagnos- tics Procedures manual for diagnostic proce- dures.
The following is an operation and description of
each system monitor :
OXYGEN SENSOR (O2S) MONITOR
Effective control of exhaust emissions is achieved by an oxygen feedback system. The most important element of the feedback system is the O2S. The O2S is located in the exhaust path. Once it reaches oper- ating temperature 300° to 350°C (572° to 662°F), the sensor generates a voltage that is inversely propor- tional to the amount of oxygen in the exhaust. The information obtained by the sensor is used to calcu- late the fuel injector pulse width. This maintains a 14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio, the catalyst works best to remove hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxide (NOx) from the exhaust.
The O2S is also the main sensing element for the
Catalyst and Fuel Monitors.
manners:
The O2S can fail in any or all of the following † slow response rate † reduced output voltage † dynamic shift † shorted or open circuits Response rate is the time required for the sensor to switch from lean to rich once it is exposed to a richer than optimum A/F mixture or vice versa. As the sen- sor starts malfunctioning, it could take longer to
DR
detect the changes in the oxygen content of the exhaust gas.
The output voltage of the O2S ranges from 0 to 1
volt. A good sensor can easily generate any output voltage in this range as it is exposed to different con- centrations of oxygen. To detect a shift in the A/F mixture (lean or rich), the output voltage has to change beyond a threshold value. A malfunctioning sensor could have difficulty changing beyond the threshold value.OXYGEN SENSOR HEATER MONITOR
If there is an oxygen sensor (O2S) shorted to volt- age DTC, as well as a O2S heater DTC, the O2S fault MUST be repaired first. Before checking the O2S fault, verify that the heater circuit is operating correctly.
Effective control of exhaust emissions is achieved by an oxygen feedback system. The most important element of the feedback system is the O2S. The O2S is located in the exhaust path. Once it reaches oper- ating temperature 300° to 350°C (572 ° to 662°F), the sensor generates a voltage that is inversely propor- tional to the amount of oxygen in the exhaust. The information obtained by the sensor is used to calcu- late the fuel injector pulse width. This maintains a 14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio, the catalyst works best to remove hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxide (NOx) from the exhaust.
The voltage readings taken from the O2S sensor are very temperature sensitive. The readings are not accurate below 300°C. Heating of the O2S sensor is done to allow the engine controller to shift to closed loop control as soon as possible. The heating element used to heat the O2S sensor must be tested to ensure that it is heating the sensor properly.
The O2S sensor circuit is monitored for a drop in voltage. The sensor output is used to test the heater by isolating the effect of the heater element on the O2S sensor output voltage from the other effects.
LEAK DETECTION PUMP MONITOR (IF EQUIPPED) The leak detection assembly incorporates two pri- mary functions: it must detect a leak in the evapora- tive system and seal the evaporative system so the leak detection test can be run.
The primary components within the assembly are: A three port solenoid that activates both of the func- tions listed above; a pump which contains a switch, two check valves and a spring/diaphragm, a canister vent valve (CVV) seal which contains a spring loaded vent seal valve.
Immediately after a cold start, between predeter- mined temperature thresholds limits, the three port solenoid is briefly energized. This initializes the
DR EMISSIONS CONTROL (Continued)
pump by drawing air into the pump cavity and also closes the vent seal. During non test conditions the vent seal is held open by the pump diaphragm assembly which pushes it open at the full travel posi- tion. The vent seal will remain closed while the pump is cycling due to the reed switch triggering of the three port solenoid that prevents the diaphragm assembly from reaching full travel. After the brief initialization period, the solenoid is de-energized allowing atmospheric pressure to enter the pump cavity, thus permitting the spring to drive the dia- phragm which forces air out of the pump cavity and into the vent system. When the solenoid is energized and de energized, the cycle is repeated creating flow in typical diaphragm pump fashion. The pump is con- trolled in 2 modes:
Pump Mode: The pump is cycled at a fixed rate to achieve a rapid pressure build in order to shorten the overall test length.
Test Mode: The solenoid is energized with a fixed duration pulse. Subsequent fixed pulses occur when the diaphragm reaches the Switch closure point.
The spring in the pump is set so that the system will achieve an equalized pressure of about 7.5” H20. The cycle rate of pump strokes is quite rapid as the system begins to pump up to this pressure. As the pressure increases, the cycle rate starts to drop off. If there is no leak in the system, the pump would even- tually stop pumping at the equalized pressure. If there is a leak, it will continue to pump at a rate rep- resentative of the flow characteristic of the size of the leak. From this information we can determine if the leak is larger than the required detection limit (cur- rently set at .040” orifice by CARB). If a leak is revealed during the leak test portion of the test, the test is terminated at the end of the test mode and no further system checks will be performed.
After passing the leak detection phase of the test, system pressure is maintained by turning on the LDP’s solenoid until the purge system is activated. Purge activation in effect creates a leak. The cycle rate is again interrogated and when it increases due to the flow through the purge system, the leak check portion of the diagnostic is complete.
The canister vent valve will unseal the system after completion of the test sequence as the pump diaphragm assembly moves to the full travel position. Evaporative system functionality will be verified by using the stricter evap purge flow monitor. At an appropriate warm idle the LDP will be energized to seal the canister vent. The purge flow will be clocked up from some small value in an attempt to see a shift in the 02 control system. If fuel vapor, indicated by a shift in the 02 control, is present the test is passed. If not, it is assumed that the purge system is
EMISSIONS CONTROL
25 - 3
not functioning in some respect. The LDP is again turned off and the test is ended.
MISFIRE MONITOR
Excessive engine misfire results in increased cata- lyst temperature and causes an increase in HC emis- sions. Severe misfires could cause catalyst damage. To prevent catalytic convertor damage, the PCM monitors engine misfire.
The Powertrain Control Module (PCM) monitors for misfire during most engine operating conditions (positive torque) by looking at changes in the crank- shaft speed. If a misfire occurs the speed of the crankshaft will vary more than normal.
FUEL SYSTEM MONITOR
To comply with clean air regulations, vehicles are equipped with catalytic converters. These converters reduce the emission of hydrocarbons, oxides of nitro- gen and carbon monoxide. The catalyst works best when the Air Fuel (A/F) ratio is at or near the opti- mum of 14.7 to 1.
The PCM is programmed to maintain the optimum air/fuel ratio of 14.7 to 1. This is done by making short term corrections in the fuel injector pulse width based on the O2S sensor output. The programmed memory acts as a self calibration tool that the engine controller uses to compensate for variations in engine specifications, sensor tolerances and engine fatigue over the life span of the engine. By monitoring the actual fuel-air ratio with the O2S sensor (short term) and multiplying that with the program long-term (adaptive) memory and comparing that to the limit, it can be determined whether it will pass an emis- sions test. If a malfunction occurs such that the PCM cannot maintain the optimum A/F ratio, then the MIL will be illuminated.
CATALYST MONITOR
To comply with clean air regulations, vehicles are equipped with catalytic converters. These converters reduce the emission of hydrocarbons, oxides of nitro- gen and carbon monoxide.
Normal vehicle miles or engine misfire can cause a catalyst to decay. This can increase vehicle emissions and deteriorate engine performance, driveability and fuel economy.
The catalyst monitor uses dual oxygen sensors (O2S’s) to monitor the efficiency of the converter. The dual O2S’s sensor strategy is based on the fact that as a catalyst deteriorates, its oxygen storage capacity and its efficiency are both reduced. By monitoring the oxygen storage capacity of a catalyst, its effi- ciency can be indirectly calculated. The upstream O2S is used to detect the amount of oxygen in the exhaust gas before the gas enters the catalytic con-
EMISSIONS CONTROL
25 - 4
EMISSIONS CONTROL (Continued)verter. The PCM calculates the A/F mixture from the output of the O2S. A low voltage indicates high oxy- gen content (lean mixture). A high voltage indicates a low content of oxygen (rich mixture).
When the upstream O2S detects a lean condition, there is an abundance of oxygen in the exhaust gas. A functioning converter would store this oxygen so it can use it for the oxidation of HC and CO. As the converter absorbs the oxygen, there will be a lack of oxygen downstream of the converter. The output of the downstream O2S will indicate limited activity in this condition.
As the converter loses the ability to store oxygen, the condition can be detected from the behavior of the downstream O2S. When the efficiency drops, no chemical reaction takes place. This means the con- centration of oxygen will be the same downstream as upstream. The output voltage of the downstream O2S copies the voltage of the upstream sensor. The only difference is a time lag (seen by the PCM) between the switching of the O2S’s.
To monitor the system, the number of lean-to-rich switches of upstream and downstream O2S’s is counted. The ratio of downstream switches to upstream switches is used to determine whether the catalyst is operating properly. An effective catalyst will have fewer downstream switches than it has upstream switches i.e., a ratio closer to zero. For a totally ineffective catalyst, this ratio will be one-to- one, indicating that no oxidation occurs in the device. The system must be monitored so that when cata- lyst efficiency deteriorates and exhaust emissions increase to over the legal limit, the MIL will be illu- minated.
DESCRIPTION - TRIP DEFINITION
The term “Trip” has different meanings depending on what the circumstances are. If the MIL (Malfunc- tion Indicator Lamp) is OFF, a Trip is defined as when the Oxygen Sensor Monitor and the Catalyst Monitor have been completed in the same drive cycle. When any Emission DTC is set, the MIL on the dash is turned ON. When the MIL is ON, it takes 3
good trips to turn the MIL OFF. In this case, it depends on what type of DTC is set to know what a “Trip” is.For the Fuel Monitor or Mis-Fire Monitor (contin- uous monitor), the vehicle must be operated in the “Similar Condition Window” for a specified amount of time to be considered a Good Trip.
If a Non-Contiuous OBDII Monitor fails twice in a row and turns ON the MIL, re-running that monitor which previously failed, on the next start-up and passing the monitor, is considered to be a Good Trip. These will include the following:
† Oxygen Sensor
DR
† Catalyst Monitor † Purge Flow Monitor † Leak Detection Pump Monitor (if equipped) † EGR Monitor (if equipped) † Oxygen Sensor Heater Monitor If any other Emission DTC is set (not an OBDII Monitor), a Good Trip is considered to be when the Oxygen Sensor Monitor and Catalyst Monitor have been completed; or 2 Minutes of engine run time if the Oxygen Sensor Monitor or Catalyst Monitor have been stopped from running.
It can take up to 2 Failures in a row to turn on the MIL. After the MIL is ON, it takes 3 Good Trips to turn the MIL OFF. After the MIL is OFF, the PCM will self-erase the DTC after 40 Warm-up cycles. A Warm-up cycle is counted when the ECT (Engine Coolant Temperature Sensor) has crossed 160°F and has risen by at least 40°F since the engine has been started.
DESCRIPTION - COMPONENT MONITORS
There are several components that will affect vehi- cle emissions if they malfunction. If one of these com- ponents malfunctions the Malfunction Indicator Lamp (MIL) will illuminate.
Some of the component monitors are checking for proper operation of the part. Electrically operated components now have input (rationality) and output (functionality) checks. Previously, a component like the Throttle Position sensor (TPS) was checked by the PCM for an open or shorted circuit. If one of these conditions occurred, a DTC was set. Now there is a check to ensure that the component is working. This is done by watching for a TPS indication of a greater or lesser throttle opening than MAP and engine rpm indicate. In the case of the TPS, if engine vacuum is high and engine rpm is 1600 or greater, and the TPS indicates a large throttle opening, a DTC will be set. The same applies to low vacuum if the TPS indicates a small throttle opening.
All open/short circuit checks, or any component that has an associated limp-in, will set a fault after 1
trip with the malfunction present. Components with- out an associated limp-in will take two trips to illu- minate the MIL.OPERATION
OPERATION
The Powertrain Control Module (PCM) monitors many different circuits in the fuel injection, ignition, emission and engine systems. If the PCM senses a problem with a monitored circuit often enough to indicate an actual problem, it stores a Diagnostic Trouble Code (DTC) in the PCM’s memory. If the
DR EMISSIONS CONTROL (Continued)
EMISSIONS CONTROL
25 - 5
problem is repaired or ceases to exist, the PCM can- cels the code after 40 warm-up cycles. Diagnostic trouble codes that affect vehicle emissions illuminate the Malfunction Indicator Lamp (MIL). The MIL is displayed as an engine icon (graphic) on the instru- ment panel. Refer to Malfunction Indicator Lamp in this section.
Certain criteria must be met before the PCM stores a DTC in memory. The criteria may be a spe- cific range of engine RPM, engine temperature, and/or input voltage to the PCM.
The PCM might not store a DTC for a monitored circuit even though a malfunction has occurred. This may happen because one of the DTC criteria for the circuit has not been met. For example, assume the diagnostic trouble code criteria requires the PCM to monitor the circuit only when the engine operates between 750 and 2000 RPM. Suppose the sensor’s output circuit shorts to ground when engine operates above 2400 RPM (resulting in 0 volt input to the PCM). Because the condition happens at an engine speed above the maximum threshold (2000 rpm), the PCM will not store a DTC.
There are several operating conditions for which the PCM monitors and sets DTC’s. Refer to Moni- tored Systems, Components, and Non-Monitored Cir- cuits in this section.
Technicians must retrieve stored DTC’s by connect- ing the DRB scan tool (or an equivalent scan tool) to the 16–way data link connector. The connector is located on the bottom edge of the instrument panel near the steering column (Fig. 1).
NOTE: Various diagnostic procedures may actually cause a diagnostic monitor to set a DTC. For instance, pulling a spark plug wire to perform a spark test may set the misfire code. When a repair is completed and verified, connect the DRB scan tool to the 16–way data link connector to erase all DTC’s and extinguish the MIL.
OPERATION - TASK MANAGER
The Task Manager determines which tests happen when and which functions occur when. Many of the diagnostic steps required by OBD II must be per- formed under specific operating conditions. The Task Manager software organizes and prioritizes the diag- nostic procedures. The job of the Task Manager is to determine if conditions are appropriate for tests to be run, monitor the parameters for a trip for each test, and record the results of the test. Following are the responsibilities of the Task Manager software: † Test Sequence † MIL Illumination † Diagnostic Trouble Codes (DTCs) † Trip Indicator
Fig.1DATALINKCONNECTORLOCATION-
TYPICAL
1 - 16-WAY DATA LINK CONNECTOR
† Freeze Frame Data Storage † Similar Conditions Window
Test Sequence
In many instances, emissions systems must fail diagnostic tests more than once before the PCM illu- minates the MIL. These tests are know as ’two trip monitors.’ Other tests that turn the MIL lamp on after a single failure are known as ’one trip moni- tors.’ A trip is defined as ’start the vehicle and oper- ate it to meet the criteria necessary to run the given monitor.’
Many of the diagnostic tests must be performed under certain operating conditions. However, there are times when tests cannot be run because another test is in progress (conflict), another test has failed (pending) or the Task Manager has set a fault that may cause a failure of the test (suspend).
† Pending
Under some situations the Task Manager will not run a monitor if the MIL is illuminated and a fault is stored from another monitor. In these situations, the Task Manager postpones monitors pending resolu- tion of the original fault. The Task Manager does not run the test until the problem is remedied. For example, when the MIL is illuminated for an Oxygen Sensor fault, the Task Manager does not run the Catalyst Monitor until the Oxygen Sensor fault is remedied. Since the Catalyst Monitor is based on sig- nals from the Oxygen Sensor, running the test would produce inaccurate results.
† Conflict
There are situations when the Task Manager does not run a test if another monitor is in progress. In
EMISSIONS CONTROL
25 - 6
EMISSIONS CONTROL (Continued)if
these situations, the effects of another monitor run- ning could result in an erroneous failure. If this con- flict is present, the monitor is not run until the conflicting condition passes. Most likely the monitor will run later after the conflicting monitor has passed. For example, the Fuel System Monitor is in progress, the Task Manager does not run the EGR Monitor. Since both tests monitor changes in air/fuel ratio and adaptive fuel compensation, the monitors will conflict with each other. † Suspend Occasionally the Task Manager may not allow a two trip fault to mature. The Task Manager will sus- pend the maturing of a fault if a condition exists that may induce an erroneous failure. This prevents illuminating the MIL for the wrong fault and allows more precis diagnosis. For example, if the PCM is storing a one trip fault for the Oxygen Sensor and the EGR monitor, the Task Manager may still run the EGR Monitor but will suspend the results until the Oxygen Sensor Monitor either passes or fails. At that point the Task Manager can determine if the EGR system is actu- ally failing or if an Oxygen Sensor is failing.
MIL Illumination
The PCM Task Manager carries out the illumina- tion of the MIL. The Task Manager triggers MIL illu- mination upon test failure, depending on monitor failure criteria.
The Task Manager Screen shows both a Requested MIL state and an Actual MIL state. When the MIL is illuminated upon completion of a test for a third trip, the Requested MIL state changes to OFF. However, the MIL remains illuminated until the next key cycle. (On some vehicles, the MIL will actually turn OFF during the third key cycle) During the key cycle for the third good trip, the Requested MIL state is OFF, while the Actual MILL state is ON. After the next key cycle, the MIL is not illuminated and both MIL states read OFF.
Diagnostic Trouble Codes (DTCs)
With OBD II, different DTC faults have different priorities according to regulations. As a result, the priorities determine MIL illumination and DTC era- sure. DTCs are entered according to individual prior- ity. DTCs with a higher priority overwrite lower priority DTCs.
Priorities
† Priority 0 —Non-emissions related trouble codes † Priority 1 — One trip failure of a two trip fault
for non-fuel system and non-misfire.
DR
for fuel system (rich/lean) or misfire.
† Priority 2 — One trip failure of a two trip fault † Priority 3 — Two trip failure for a non-fuel sys- tem and non-misfire or matured one trip comprehen- sive component fault. † Priority 4 — Two trip failure or matured fault for fuel system (rich/lean) and misfire or one trip cat- alyst damaging misfire.
Non-emissions related failures have no priority. One trip failures of two trip faults have low priority. Two trip failures or matured faults have higher pri- ority. One and two trip failures of fuel system and misfire monitor take precedence over non-fuel system and non-misfire failures.
DTC Self Erasure
With one trip components or systems, the MIL is
illuminated upon test failure and DTCs are stored.
Two trip monitors are components requiring failure in two consecutive trips for MIL illumination. Upon failure of the first test, the Task Manager enters a maturing code. If the component fails the test for a second time the code matures and a DTC is set.
After three good trips the MIL is extinguished and the Task Manager automatically switches the trip counter to a warm-up cycle counter. DTCs are auto- matically erased following 40 warm-up cycles if the component does not fail again.
For misfire and fuel system monitors, the compo- nent must pass the test under a Similar Conditions Window in order to record a good trip. A Similar Con- ditions Window is when engine RPM is within ±375
RPM and load is within ±10% of when the fault occurred.NOTE: It is important to understand that a compo- nent does not have to fail under a similar window of operation to mature. It must pass the test under a Similar Conditions Window when it failed to record a Good Trip for DTC erasure for misfire and fuel system monitors.
DTCs can be erased anytime with a DRB III. Eras- ing the DTC with the DRB III erases all OBD II information. The DRB III automatically displays a warning that erasing the DTC will also erase all OBD II monitor data. This includes all counter infor- mation for warm-up cycles, trips and Freeze Frame.
Trip Indicator
The Trip is essential for running monitors and extinguishing the MIL. In OBD II terms, a trip is a set of vehicle operating conditions that must be met for a specific monitor to run. All trips begin with a key cycle.
Good Trip The Good Trip counters are as follows:
DR EMISSIONS CONTROL (Continued) † Specific Good Trip † Fuel System Good Trip † Misfire Good Trip † Alternate Good Trip (appears as a Global Good Trip on DRB III)
† Comprehensive Components † Major Monitor † Warm-Up Cycles Specific Good Trip The term Good Trip has different meanings depending on the circumstances: † If the MIL is OFF, a trip is defined as when the Oxygen Sensor Monitor and the Catalyst Monitor have been completed in the same drive cycle. † If the MIL is ON and a DTC was set by the Fuel Monitor or Misfire Monitor (both continuous moni- tors), the vehicle must be operated in the Similar Condition Window for a specified amount of time. † If the MIL is ON and a DTC was set by a Task Manager commanded once-per-trip monitor (such as the Oxygen Sensor Monitor, Catalyst Monitor, Purge Flow Monitor, Leak Detection Pump Monitor, EGR Monitor or Oxygen Sensor Heater Monitor), a good trip is when the monitor is passed on the next start- up.† If the MIL is ON and any other emissions DTC was set (not an OBD II monitor), a good trip occurs when the Oxygen Sensor Monitor and Catalyst Mon- itor have been completed, or two minutes of engine run time if the Oxygen Sensor Monitor and Catalyst Monitor have been stopped from running.
Fuel System Good Trip To count a good trip (three required) and turn off the MIL, the following conditions must occur: † Engine in closed loop † Operating in Similar Conditions Window † Short Term multiplied by Long Term less than † Less than threshold for a predetermined time If all of the previous criteria are met, the PCM will count a good trip (three required) and turn off the MIL.
threshold
Misfire Good Trip If the following conditions are met the PCM will count one good trip (three required) in order to turn off the MIL:
† Operating in Similar Condition Window † 1000 engine revolutions with no misfire Warm-Up Cycles Once the MIL has been extinguished by the Good Trip Counter, the PCM automatically switches to a Warm-Up Cycle Counter that can be viewed on the DRB III. Warm-Up Cycles are used to erase DTCs and Freeze Frames. Forty Warm-Up cycles must occur in order for the PCM to self-erase a DTC and
EMISSIONS CONTROL
25 - 7
Freeze Frame. A Warm-Up Cycle is defined as fol- lows:† Engine coolant temperature must start below and rise above 160° F † Engine coolant temperature must rise by 40° F † No further faults occur Freeze Frame Data Storage
Once a failure occurs, the Task Manager records several engine operating conditions and stores it in a Freeze Frame. The Freeze Frame is considered one frame of information taken by an on-board data recorder. When a fault occurs, the PCM stores the input data from various sensors so that technicians can determine under what vehicle operating condi- tions the failure occurred.
The data stored in Freeze Frame is usually recorded when a system fails the first time for two trip faults. Freeze Frame data will only be overwrit- ten by a different fault with a higher priority.
CAUTION: Erasing DTCs, either with the DRB III or by disconnecting the battery, also clears all Freeze Frame data.
Similar Conditions Window
The Similar Conditions Window displays informa- tion about engine operation during a monitor. Abso- lute MAP (engine load) and Engine RPM are stored in this window when a failure occurs. There are two different Similar conditions Windows: Fuel System and Misfire.
FUEL SYSTEM † Fuel System Similar Conditions Window — An indicator that ’Absolute MAP When Fuel Sys Fail’ and ’RPM When Fuel Sys Failed’ are all in the same range when the failure occurred. Indicated by switch- ing from ’NO’ to ’YES’. † Absolute MAP When Fuel Sys Fail — The stored MAP reading at the time of failure. Informs the user at what engine load the failure occurred. † Absolute MAP — A live reading of engine load to aid the user in accessing the Similar Conditions Window. † RPM When Fuel Sys Fail — The stored RPM reading at the time of failure. Informs the user at what engine RPM the failure occurred. † Engine RPM — A live reading of engine RPM to aid the user in accessing the Similar Conditions Window. † Adaptive Memory Factor — The PCM utilizes both Short Term Compensation and Long Term Adap- tive to calculate the Adaptive Memory Factor for total fuel correction.
EMISSIONS CONTROL
25 - 8
EMISSIONS CONTROL (Continued) † Upstream O2S Volts — A live reading of the Oxygen Sensor to indicate its performance. For example, stuck lean, stuck rich, etc. † SCW Time in Window (Similar Conditions Window Time in Window) — A timer used by the PCM that indicates that, after all Similar Conditions have been met, if there has been enough good engine running time in the SCW without failure detected. This timer is used to increment a Good Trip. † Fuel System Good Trip Counter — A Trip Counter used to turn OFF the MIL for Fuel System DTCs. To increment a Fuel System Good Trip, the engine must be in the Similar Conditions Window, Adaptive Memory Factor must be less than cali- brated threshold and the Adaptive Memory Factor must stay below that threshold for a calibrated amount of time. † Test Done This Trip — Indicates that the monitor has already been run and completed during the current trip.MISFIRE † Same Misfire Warm-Up State — Indicates if the misfire occurred when the engine was warmed up (above 160° F). † In Similar Misfire Window — An indicator that ’Absolute MAP When Misfire Occurred’ and ’RPM When Misfire Occurred’ are all in the same range when the failure occurred. Indicated by switch- ing from ’NO’ to ’YES’. † Absolute MAP When Misfire Occurred — The stored MAP reading at the time of failure. Informs the user at what engine load the failure occurred. † Absolute MAP — A live reading of engine load to aid the user in accessing the Similar Conditions Window. † RPM When Misfire Occurred — The stored RPM reading at the time of failure. Informs the user at what engine RPM the failure occurred. † Engine RPM — A live reading of engine RPM to aid the user in accessing the Similar Conditions Window. † Adaptive Memory Factor — The PCM utilizes both Short Term Compensation and Long Term Adap- tive to calculate the Adaptive Memory Factor for total fuel correction. † 200 Rev Counter — Counts 0–100 720 degree cycles.† SCW Cat 200 Rev Counter — Counts when in similar conditions. † SCW FTP 1000 Rev Counter — Counts 0–4
when in similar conditions. † Misfire Good Trip Counter — Counts up to three to turn OFF the MIL. † Misfire Data— Data collected during test.DR
† Test Done This Trip— Indicates YES when the test is done.
OPERATION - NON-MONITORED CIRCUITS
The PCM does not monitor the following circuits, systems and conditions that could have malfunctions causing driveability problems. The PCM might not store diagnostic trouble codes for these conditions. However, problems with these systems may cause the PCM to store diagnostic trouble codes for other sys- tems or components. EXAMPLE: a fuel pressure problem will not register a fault directly, but could cause a rich/lean condition or misfire. This could cause the PCM to store an oxygen sensor or misfire diagnostic trouble code
FUEL PRESSURE
The fuel pressure regulator controls fuel system pressure. The PCM cannot detect a clogged fuel pump inlet filter, clogged in-line fuel filter, or a pinched fuel supply or return line. However, these could result in a rich or lean condition causing the PCM to store an oxygen sensor or fuel system diag- nostic trouble code.
SECONDARY IGNITION CIRCUIT
The PCM cannot detect an inoperative ignition coil, fouled or worn spark plugs, ignition cross firing, or open spark plug cables.
CYLINDER COMPRESSION
The PCM cannot detect uneven, low, or high engine
cylinder compression.
EXHAUST SYSTEM
The PCM cannot detect a plugged, restricted or leaking exhaust system, although it may set a fuel system fault.
FUEL INJECTOR MECHANICAL MALFUNCTIONS
The PCM cannot determine if a fuel injector is clogged, the needle is sticking or if the wrong injector is installed. However, these could result in a rich or lean condition causing the PCM to store a diagnostic trouble code for either misfire, an oxygen sensor, or the fuel system.
EXCESSIVE OIL CONSUMPTION
Although the PCM monitors engine exhaust oxygen content when the system is in closed loop, it cannot determine excessive oil consumption.
THROTTLE BODY AIR FLOW
The PCM cannot detect a clogged or restricted air
cleaner inlet or filter element.
DR EMISSIONS CONTROL (Continued)
VACUUM ASSIST
The PCM cannot detect leaks or restrictions in the vacuum circuits of vacuum assisted engine control system devices. However, these could cause the PCM to store a MAP sensor diagnostic trouble code and cause a high idle condition.
PCM SYSTEM GROUND
The PCM cannot determine a poor system ground. However, one or more diagnostic trouble codes may
EMISSIONS CONTROL
25 - 9
be generated as a result of this condition. The mod- ule should be mounted to the body at all times, also during diagnostic.
PCM CONNECTOR ENGAGEMENT
The PCM may not be able to determine spread or damaged connector pins. However, it might store diagnostic trouble codes as a result of spread connec- tor pins.
25 - 10
EVAPORATIVE EMISSIONS
EVAPORATIVE EMISSIONS
TABLE OF CONTENTS
page
DR
page
EVAPORATIVE EMISSIONS
PCV VALVE
DESCRIPTION - EVAP SYSTEM . . . . . . . . . . . . 10
SPECIFICATIONSTORQUE - EVAP SYSTEM . . . . . . . . . . . . . . 12
CCV HOSE
DESCRIPTION - 8.0L V-10
OPERATION - 8.0L V-10
EVAP/PURGE SOLENOID. . . . . . . . . . . . . . . . 12
. . . . . . . . . . . . . . . . . . 12DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 12
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 13FUEL FILLER CAP
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 16
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
DIAGNOSIS AND TESTINGDIAGNOSIS AND TESTING - PCV VALVE -
3.7L V-6/ 4.7L V-8 . . . . . . . . . . . . . . . . . . . . . . 19
DIAGNOSIS AND TESTING - PCV VALVE -
5.9L V-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 22VACUUM LINES
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 22
VAPOR CANISTER
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 13
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
REMOVALREMOVAL/INSTALLATION . . . . . . . . . . . . . . . 13
LEAK DETECTION PUMP
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 13
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 16DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 22
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 23NATURAL VAC LEAK DETECTION ASSY
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 23
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 24EVAPORATIVE EMISSIONS DESCRIPTION - EVAP SYSTEM
The evaporation control system prevents the emis- sion of fuel tank vapors into the atmosphere. When fuel evaporates in the fuel tank, the vapors pass through vent hoses or tubes into the two charcoal filled evaporative canisters. The canisters tempo- rarily hold the vapors. The Powertrain Control Mod- ule (PCM) allows intake manifold vacuum to draw vapors into the combustion chambers during certain operating conditions.
All gasoline powered engines use a duty cycle purge system. The PCM controls vapor flow by oper- ating the duty cycle EVAP purge solenoid. Refer to Duty Cycle EVAP Canister Purge Solenoid for addi- tional information.
When equipped with certain emissions packages, a Leak Detection Pump (LDP) will be used as part of the evaporative system. This pump is used as a part of OBD II requirements. Refer to Leak Detection Pump for additional information. Other emissions packages will use a Natural Vacuum Leak Detection (NVLD) system in place of the LDP. Refer to NVLD for additional information.
NOTE: The hoses used in this system are specially manufactured. If replacement becomes necessary, it is important to use only fuel resistant hose.
DR EVAPORATIVE EMISSIONS (Continued)
Certain EVAP system components can be found in
(Fig. 1).
EVAPORATIVE EMISSIONS
25 - 11
Fig.1FUELDELIVERYCOMPONENTS
1 - FUEL TANK 2 - CHECK VALVE 3 - LIQUID EXPANSION CHAMBER 4 - FUEL FILTER / FUEL PRESSURE REGULATOR 5 - QUICK-CONNECT FITTING AND FUEL LINE (TO ENGINE) 6 - EVAP LINE CONNECTION 7 - LEAK DETECTION PUMP FRESH AIR LINE
8 - LDP FRESH AIR FILTER 9 - LEAK DETECTION PUMP 10 - EVAP CANISTERS (2) 11 - FUEL TANK STRAPS (2) 12 - CHECK VALVE 13 - FUEL PUMP MODULE LOCK RING 14 - FUEL PUMP MODULE
EVAPORATIVE EMISSIONS
25 - 12
EVAPORATIVE EMISSIONS (Continued) SPECIFICATIONSTORQUE - EVAP SYSTEM
DESCRIPTION
EVAP Canister Mounting
Nuts
EVAP Canister Mounting Bracket-to-Frame Bolts Leak Detection Pump
Mounting Bolts
Leak Detection Pump Filter Mounting Bolt
N·m
11
14
11
11
CCV HOSE DESCRIPTION - 8.0L V-10
The 8.0L V-10 engine is equipped with a Crankcase Ventilation (CCV) system. The CCV system performs the same function as a conventional PCV system, but does not use a vacuum controlled valve (PCV valve). A molded vacuum tube connects manifold vacuum to the top of the right cylinder head (valve) cover. The vacuum tube connects to a fixed orifice fitting (Fig. 2) of a calibrated size 2.6 mm (0.10 inches).
DR
Ft. Lbs.
In. Lbs.
10
95
125
95
95
fitting meters the amount of crankcase vapors drawn out of the engine. The fixed orifice fitting is grey in color. A similar fitting (but does not contain a fixed orifice) is used on the left cylinder head (valve) cover. This fitting is black in color. Do not inter- change these two fittings.
When the engine is operating, fresh air enters the engine and mixes with crankcase vapors. Manifold vacuum draws the vapor/air mixture through the fixed orifice and into the intake manifold. The vapors are then consumed during engine combustion.
EVAP/PURGE SOLENOID DESCRIPTION
The duty cycle EVAP canister purge solenoid is located in the engine compartment. It is attached to the side of the Power Distribution Center (PDC).
OPERATION
The Powertrain Control Module (PCM) operates
the solenoid.
During the cold start warm-up period and the hot start time delay, the PCM does not energize the sole- noid. When de-energized, no vapors are purged. The PCM de-energizes the solenoid during open loop oper- ation.
The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. During closed loop operation, the PCM ener- gizes and de-energizes the solenoid 5 or 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time the solenoid energizes. The PCM adjusts solenoid pulse width based on engine operating condition.
Fig.2FIXEDORIFICEFITTING-8.0LV-10ENGINE-
TYPICAL
1 - VACUUM TUBE 2 - FIXED ORIFICE FITTING 3 - COIL PACKS 4 - ORIFICE FITTING HOSE CONNECTIONS
OPERATION - 8.0L V-10
A molded vacuum tube connects manifold vacuum to the top of the right cylinder head (valve) cover. The vacuum tube connects to a fixed orifice fitting (Fig. 2) of a calibrated size 2.6 mm (0.10 inches). The
DR EVAP/PURGE SOLENOID (Continued) REMOVAL
The duty cycle EVAP canister purge solenoid is located in the engine compartment. It is attached to the side of the Power Distribution Center (PDC) (Fig. 3).
(1) Disconnect electrical wiring connector at sole-
noid.
(2) Disconnect vacuum harness at solenoid (Fig. 3). (3) Remove solenoid from mounting bracket.
Fig.3EVAP/DUTYCYCLEPURGESOLENOID
1 - MOUNTING BRACKET 2 - VACUUM HARNESS 3 - DUTY CYCLE SOLENOID 4 - TEST PORT CAP AND TEST PORT
INSTALLATION
(1) Install solenoid assembly to mounting bracket. (2) Connect vacuum harness. (3) Connect electrical connector.
FUEL FILLER CAP DESCRIPTION
The plastic fuel tank filler tube cap is threaded onto the end of the fuel fill tube. Certain models are equipped with a 1/4 turn cap.
OPERATION
The loss of any fuel or vapor out of fuel filler tube is prevented by the use of a pressure-vacuum fuel fill cap. Relief valves inside the cap will release fuel tank pressure at predetermined pressures. Fuel tank vac- uum will also be released at predetermined values.
EVAPORATIVE EMISSIONS
25 - 13
This cap must be replaced by a similar unit if replacement is necessary. This is in order for the sys- tem to remain effective.
to relieve tank pressure.
CAUTION: Remove fill cap before servicing any fuel system component If equipped with a Leak Detection Pump (LDP), or NVLD system, the cap must be tightened securely. If cap is left loose, a Diagnostic Trouble Code (DTC) may be set.
REMOVAL
REMOVAL/INSTALLATION
If replacement of the 1/4 turn fuel tank filler tube cap is necessary, it must be replaced with an identi- cal cap to be sure of correct system operation.
CAUTION: Remove the fuel tank filler tube cap to relieve fuel tank pressure. The cap must be removed prior to disconnecting any fuel system component or before draining the fuel tank.
LEAK DETECTION PUMP DESCRIPTION
Vehicles equipped with JTEC engine control mod- ules use a leak detection pump. Vehicles equipped with NGC engine control modules use an NVLD pump. Refer to Natural Vacuum - Leak Detection (NVLD) for additional information.
The evaporative emission system is designed to prevent the escape of fuel vapors from the fuel sys- tem (Fig. 4). Leaks in the system, even small ones, can allow fuel vapors to escape into the atmosphere. Government regulations require onboard testing to make sure that the evaporative (EVAP) system is functioning properly. The leak detection system tests for EVAP system leaks and blockage. It also performs self-diagnostics. During self-diagnostics, the Power- train Control Module (PCM) first checks the Leak Detection Pump (LDP) for electrical and mechanical faults. If the first checks pass, the PCM then uses the LDP to seal the vent valve and pump air into the system to pressurize it. If a leak is present, the PCM will continue pumping the LDP to replace the air that leaks out. The PCM determines the size of the leak based on how fast/long it must pump the LDP as it tries to maintain pressure in the system.
EVAPORATIVE EMISSIONS
25 - 14
LEAK DETECTION PUMP (Continued)DR
powered by engine vacuum. It pumps air into the EVAP system to develop a pressure of about 7.59
H2O (1/4) psi. A reed switch in the LDP allows the PCM to monitor the position of the LDP diaphragm. The PCM uses the reed switch input to monitor how fast the LDP is pumping air into the EVAP system. This allows detection of leaks and blockage. The LDP assembly consists of several parts (Fig. 5). The sole- noid is controlled by the PCM, and it connects the upper pump cavity to either engine vacuum or atmo- spheric pressure. A vent valve closes the EVAP sys- tem to atmosphere, sealing the system during leak testing. The pump section of the LDP consists of a diaphragm that moves up and down to bring air in through the air filter and inlet check valve, and pump it out through an outlet check valve into the EVAP system. The diaphragm is pulled up by engine vacuum, and pushed down by spring pressure, as the LDP solenoid turns on and off. The LDP also has a magnetic reed switch to signal diaphragm position to the PCM. When the diaphragm is down, the switch is closed, which sends a 12 V (system voltage) signal to the PCM. When the diaphragm is up, the switch is open, and there is no voltage sent to the PCM. This allows the PCM to monitor LDP pumping action as it turns the LDP solenoid on and off.LDP AT REST (NOT POWERED)
When the LDP is at rest (no electrical/vacuum) the diaphragm is allowed to drop down if the internal (EVAP system) pressure is not greater than the return spring. The LDP solenoid blocks the engine vacuum port and opens the atmospheric pressure port connected through the EVAP system air filter. The vent valve is held open by the diaphragm. This allows the canister to see atmospheric pressure (Fig. 6).
DIAPHRAGM UPWARD MOVEMENT
When the PCM energizes the LDP solenoid, the solenoid blocks the atmospheric port leading through the EVAP air filter and at the same time opens the engine vacuum port to the pump cavity above the diaphragm. The diaphragm moves upward when vac- uum above the diaphragm exceeds spring force. This upward movement closes the vent valve. It also causes low pressure below the diaphragm, unseating the inlet check valve and allowing air in from the EVAP air filter. When the diaphragm completes its upward movement, the LDP reed switch turns from closed to open (Fig. 7).
DIAPHRAGM DOWNWARD MOVEMENT
Based on reed switch input, the PCM de-energizes the LDP solenoid, causing it to block the vacuum port, and open the atmospheric port. This connects
Fig.4TYPICALSYSTEMCOMPONENTS
1 - Throttle Body 2 - Service Vacuum Supply Tee (SVST) 3 - LDP Solenoid 4 - EVAP System Air Filter 5 - LDP Vent Valve 6 - EVAP Purge Orifice 7 - EVAP Purge Solenoid 8 - Service Port 9 - To Fuel Tank 10 - EVAP Canister 11 - LDP 12 - Intake Air Plenum
EVAP LEAK DETECTION SYSTEM COMPONENTS
Service Port: Used with special tools like the Miller Evaporative Emissions Leak Detector (EELD) to test for leaks in the system.
EVAP Purge Solenoid: The PCM uses the EVAP purge solenoid to control purging of excess fuel vapors stored in the EVAP canister. It remains closed during leak testing to prevent loss of pressure.
EVAP Canister: The EVAP canister stores fuel
vapors from the fuel tank for purging.
EVAP Purge Orifice: Limits purge volume. EVAP System Air Filter: Provides air to the LDP for pressurizing the system. It filters out dirt while allowing a vent to atmosphere for the EVAP system.
OPERATION
The main purpose of the LDP is to pressurize the fuel system for leak checking. It closes the EVAP sys- tem vent to atmospheric pressure so the system can be pressurized for leak testing. The diaphragm is
DR LEAK DETECTION PUMP (Continued)
EVAPORATIVE EMISSIONS
25 - 15
Fig.5EVAPLEAKDETECTIONSYSTEM
COMPONENTS
1 - Reed Switch 2 - Solenoid 3 - Spring 4 - Pump Cavity 5 - Diaphragm 6 - Inlet Check Valve 7 - Vent Valve 8 - From Air Filter 9 - To Canister 10 - Outlet Check Valve 11 - Engine Vacuum
the upper pump cavity to atmosphere through the EVAP air filter. The spring is now able to push the diaphragm down. The downward movement of the diaphragm closes the inlet check valve and opens the outlet check valve pumping air into the evaporative system. The LDP reed switch turns from open to closed, allowing the PCM to monitor LDP pumping (diaphragm up/down) activity (Fig. 8). During the pumping mode, the diaphragm will not move down far enough to open the vent valve. The pumping cycle is repeated as the solenoid is turned on and off. When the evaporative system begins to pressurize, the pressure on the bottom of the diaphragm will begin to oppose the spring pressure, slowing the pumping action. The PCM watches the time from when the solenoid is de-energized, until the dia- phragm drops down far enough for the reed switch to change from opened to closed. If the reed switch changes too quickly, a leak may be indicated. The longer it takes the reed switch to change state, the tighter the evaporative system is sealed. If the sys- tem pressurizes too quickly, a restriction somewhere in the EVAP system may be indicated.
Fig.6LDPATREST
1 - Diaphragm 2 - Inlet Check Valve (Closed) 3 - Vent Valve (Open) 4 - From Air Filter 5 - To Canister 6 - Outlet Check Valve (Closed) 7 - Engine Vacuum (Closed)
PUMPING ACTION
Action : During portions of this test, the PCM uses the reed switch to monitor diaphragm movement. The solenoid is only turned on by the PCM after the reed switch changes from open to closed, indicating that the diaphragm has moved down. At other times during the test, the PCM will rapidly cycle the LDP solenoid on and off to quickly pressurize the system. During rapid cycling, the diaphragm will not move enough to change the reed switch state. In the state of rapid cycling, the PCM will use a fixed time inter- val to cycle the solenoid. If the system does not pass the EVAP Leak Detection Test, the following DTCs may be set: † P0442 - EVAP LEAK MONITOR 0.0409 LEAK DETECTED † P0455 - EVAP LEAK MONITOR LARGE LEAK † P0456 - EVAP LEAK MONITOR 0.0209 LEAK DETECTED † P1486 - EVAP LEAK MON PINCHED HOSE FOUND† P1494 - LEAK DETECTION PUMP SW OR MECH FAULT † P1495 - LEAK DETECTION PUMP SOLENOID
DETECTED
CIRCUIT
EVAPORATIVE EMISSIONS
25 - 16
LEAK DETECTION PUMP (Continued)DR
Fig.7DIAPHRAGMUPWARDMOVEMENT
Fig.8DIAPHRAGMDOWNWARDMOVEMENT
1 - Diaphragm 2 - Inlet Check Valve (Open) 3 - Vent Valve (Closed) 4 - From Air Filter 5 - To Canister 6 - Outlet Check Valve (Closed) 7 - Engine Vacuum (Open)
REMOVAL
The Leak Detection Pump (LDP) and LDP filter are attached to the front of the EVAP canister mounting bracket (Fig. 9). This is located near the front of the fuel tank. The LDP and LDP filter are replaced (serviced) as one unit. (1) Raise and support vehicle. (2) Carefully remove hose at LDP filter. (3) Remove LDP filter mounting bolt and remove
from vehicle.
(4) Carefully remove vapor/vacuum lines at LDP. (5) Disconnect electrical connector at LDP. (6) Remove LDP mounting bolt and remove LDP
from vehicle.
INSTALLATION
The LDP and LDP filter are attached to the front of the EVAP canister mounting bracket. The LDP and LDP filter are replaced (serviced) as one unit.
(1) Install LDP to mounting bracket. Refer to
Torque Specifications.
Torque Specifications.
(2) Install LDP filter to mounting bracket. Refer to
(3) Carefully install vapor/vacuum lines to LDP, and install hose to LDP filter. The vapor/vacuum lines and hoses must be firmly connected. Check the vapor/vacuum lines at the LDP, LDP
1 - Diaphragm 2 - Inlet Check Valve (Closed) 3 - Vent Valve (Closed) 4 - From Air Filter 5 - To Canister 6 - Outlet Check Valve (Open) 7 - Engine Vacuum (Closed)
filter and EVAP canister purge solenoid for damage or leaks. If a leak is present, a Diagnos- tic Trouble Code (DTC) may be set.
(4) Connect electrical connector to LDP.
PCV VALVE DESCRIPTION
3.7L V-6 / 4.7L V-8
The 3.7L V-6 and 4.7L V-8 engines are equipped with a closed crankcase ventilation system and a Positive Crankcase Ventilation (PCV) valve.
This system consists of: † a PCV valve mounted to the oil filler housing (Fig. 10). The PCV valve is sealed to the oil filler housing with an o-ring.
† the air cleaner housing † two interconnected breathers threaded into the † tubes and hoses to connect the system compo-
rear of each cylinder head (Fig. 11).
nents.
DR PCV VALVE (Continued)
EVAPORATIVE EMISSIONS
25 - 17
Fig.9LDPANDLDPFILTERLOCATION
1 - LDP 2 - LDP MOUNTING BOLT 3 - ELEC. CONNEC. 4 - FILTER MOUNTING BOLT 5 - LDP FILTER 6 - CONNECTING HOSE 7 - EVAP CANISTER MOUNTING BRACKET 8 - EVAP CANISTERS (2)
5.7L V-8
The 5.7L V-8 engine is equipped with a closed crankcase ventilation system and a Positive Crank- case Ventilation (PCV) valve.
This system consists of: † a PCV valve mounted into the top of the intake manifold, located to the right / rear of the throttle body (Fig. 12). The PCV valve is sealed to the intake manifold with 2 o-rings (Fig. 13).
† passages in the intake manifold. † tubes and hoses to connect the system compo-
nents.
Fig.10PCVVALVE-3.7LV-6/4.7LV-8
1 - O-RING 2 - LOCATING TABS 3 - CAM LOCK 4 - OIL FILLER TUBE 5 - PCV LINE/HOSE 6 - PCV VALVE
5.9L V-8
The 5.9L V-8 engine is equipped with a closed crankcase ventilation system and a positive crank- case ventilation (PCV) valve.
This system consists of a PCV valve mounted on the cylinder head (valve) cover with a hose extending from the valve to the intake manifold (Fig. 14). Another hose connects the opposite cylinder head (valve) cover to the air cleaner housing to provide a source of clean air for the system. A separate crank- case breather/filter is not used.
Fig.11CRANKCASEBREATHERS(2)-3.7LV-6/
4.7LV-8
1 - CRANKCASE BREATHERS (2) 2 - REAR OF ENGINE
OPERATION
The PCV system operates by engine intake mani- fold vacuum (Fig. 15). Filtered air is routed into the
EVAPORATIVE EMISSIONS
25 - 18
PCV VALVE (Continued)DR
Fig.14PCVVALVE/HOSE-5.9LV-8
1 - PCV VALVE 2 - PCV VALVE HOSE CONNECTIONS
ifold. The PCV system manages crankcase pressure and meters blow by gases to the intake system, reducing engine sludge formation.
Fig.12LOCATION5.7LPCVVALVE
1 - TOP OF INTAKE MANIFOLD 2 - THROTTLE BODY 3 - AIR RESONATOR 4 - PCV VALVE
Fig.15TYPICALCLOSEDCRANKCASE
VENTILATIONSYSTEM
1 - THROTTLE BODY 2 - AIR CLEANER 3 - AIR INTAKE 4 - PCV VALVE 5 - COMBUSTION CHAMBER 6 - BLOW-BY GASES 7 - CRANKCASE BREATHER/FILTER
Fig.135.7LPCVVALVE
1 - PCV VALVE 2 - O-RINGS 3 - ALIGNMENT TABS
crankcase through the air cleaner hose. The metered air, along with crankcase vapors, are drawn through the PCV valve and into a passage in the intake man-
The PCV valve contains a spring loaded plunger. This plunger meters the amount of crankcase vapors routed into the combustion chamber based on intake manifold vacuum.
When the engine is not operating or during an engine pop-back, the spring forces the plunger back against the seat (Fig. 16). This will prevent vapors from flowing through the valve.
DR PCV VALVE (Continued)
EVAPORATIVE EMISSIONS
25 - 19
(3) After valve is removed, check condition of valve o-ring (Fig. 19). Also, PCV valve should rattle when shaken.
(4) Reconnect PCV valve to its connecting line/
hose.
(5) Start engine and bring to idle speed. (6) If valve is not plugged, a hissing noise will be heard as air passes through valve. Also, a strong vac- uum should be felt with a finger placed at valve inlet.
(7) If vacuum is not felt at valve inlet, check line/ hose for kinks or for obstruction. If necessary, clean out intake manifold fitting at rear of manifold. Do this by turning a 1/4 inch drill (by hand) through the fitting to dislodge any solid particles. Blow out the fitting with shop air. If necessary, use a smaller drill to avoid removing any metal from the fitting.
(8) Do not attempt to clean the old PCV valve. (9) Return PCV valve back to oil filler tube by placing valve locating tabs (Fig. 19) into cam lock. Press PCV valve in and rotate valve upward. A slight click will be felt when tabs have engaged cam lock. Valve should be pointed towards rear of vehicle.
(10) Connect PCV line/hose and connecting rubber
hose to PCV valve.
(11) Disconnect rubber hose from fresh air fitting at air cleaner resonator box. Start engine and bring to idle speed. Hold a piece of stiff paper (such as a parts tag) loosely over the opening of the discon- nected rubber hose.
(12) The paper should be drawn against the hose opening with noticeable force. This will be after allowing approximately one minute for crankcase pressure to reduce.
(13) If vacuum is not present, disconnect each PCV system hose at top of each crankcase breather (Fig. 20). Check for obstructions or restrictions.
(14) If vacuum is still not present, remove each PCV system crankcase breather (Fig. 20) from each cylinder head. Check for obstructions or restrictions. If plugged, replace breather. Tighten breather to 12
N·m (106 in. lbs.) torque. Do not attempt to clean breather.(15) If vacuum is still not present, disconnect each PCV system hose at each fitting, and at each check valve (Fig. 21). Check for obstructions or restrictions.
DIAGNOSIS AND TESTING - PCV VALVE - 5.9L V-8
(1) With engine idling, remove the PCV valve from the valve is not cylinder head (valve) cover. plugged, a hissing noise will be heard as air passes through the valve. Also, a strong vacuum should be felt at the valve inlet (Fig. 22).
If
(2) Return the PCV valve into the valve cover. Remove the fitting and air hose at the opposite valve
Fig.16ENGINEOFFORENGINEBACKFIRE-NO
VAPORFLOW
During periods of high manifold vacuum, such as idle or cruising speeds, vacuum is sufficient to com- pletely compress spring. It will then pull the plunger to the top of the valve (Fig. 17). In this position there is minimal vapor flow through the valve.
Fig.17HIGHINTAKEMANIFOLDVACUUM-
MINIMALVAPORFLOW
During periods of moderate manifold vacuum, the plunger is only pulled part way back from inlet. This results in maximum vapor flow through the valve (Fig. 18).
Fig.18MODERATEINTAKEMANIFOLDVACUUM-
MAXIMUMVAPORFLOW DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - PCV VALVE - 3.7L V-6/ 4.7L V-8
(1) Disconnect PCV line/hose (Fig. 19) by discon- necting rubber connecting hose at PCV valve fitting. (2) Remove PCV valve at oil filler tube by rotating PCV valve downward until locating tabs have been freed at cam lock (Fig. 19). After tabs have cleared, pull valve straight out from filler tube. To prevent damage to PCV valve locating tabs, valve must be pointed downward for removal. Do not force valve from oil filler tube.
EVAPORATIVE EMISSIONS
25 - 20
PCV VALVE (Continued)DR
Fig.21CHECKVALVES-PCVSYSTEM-3.7LV-6/
4.7LV-8
1 - CONNECTING HOSES 2 - CHECK VALVES
Fig.19PCVVALVE-3.7LV-6/4.7LV-8
1 - O-RING 2 - LOCATING TABS 3 - CAM LOCK 4 - OIL FILLER TUBE 5 - PCV LINE/HOSE 6 - PCV VALVE
Fig.20CRANKCASEBREATHERS(2)-3.7LV-6/
4.7LV-8
1 - CRANKCASE BREATHERS (2) 2 - REAR OF ENGINE
cover. Loosely hold a piece of stiff paper, such as a parts tag, over the opening (rubber grommet) at the valve cover (Fig. 23).
Fig.22VACUUMCHECKATPCV-5.9LV-8
1 - PCV VALVE GROMMET 2 - PCV HOSE 3 - PCV VALVE
