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The Engine Control Module (ECM) is bolted to the left side of the engine below the intake manifold (Fig. 2).
NOTE: ECM Inputs:
† Accelerator Pedal Position Sensor (APPS) Volts † APPS1 Signal — For off engine APPS † APPS2 Signal — For off engine APPS † APPS Idle Validation Switches #1 and #2
† Battery voltage † Camshaft Position Sensor (CMP) † CCD bus (+) circuits † CCD bus (-) circuits † Crankshaft Position Sensor (CKP) † Data link connection for DRB scan tool † Engine Coolant Temperature (ECT) sensor † Ground circuits † Fuel Pressure Sensor † Battery Temperature † Fan speed † Inlet Air Temperature Sensor/Pressure Sensor † Intake Air Temperature Sensor/MAP Sensor † Oil Pressure SWITCH † Power ground † Sensor return † Signal ground † Water-In-Fuel (WIF) sensorNOTE: ECM Outputs:
Fig.2DIESELECM
1 - ENGINE CONTROL MODULE (ECM) 2 - ECM MOUNTING BOLT 3 - 50-WAY CONNECTOR 4 - SUPPORT PLATE 5 - 60-WAY CONNECTOR
OPERATION - ECM
The main function of the Engine Control Module (ECM) is to electrically control the fuel system. The Powertrain Control Module (PCM) does not control the fuel system.
flashed or re-calibrated,
The ECM can adapt its programming to meet changing operating conditions. If the ECM has been replaced, the ECM must learn the Accelerator Pedal Position Sensor (APPS) idle voltage. Failure to learn this voltage may result in unnecessary diagnos- tic trouble codes. Refer to ECM Removal/Instal- lation for learning procedures.
The ECM receives input signals from various switches and sensors. Based on these inputs, the ECM regulates various engine and vehicle operations through different system components. These compo- nents are referred to as ECM Outputs. The sensors and switches that provide inputs to the ECM are considered ECM Inputs.
After inputs are received by the ECM, certain sen- sors, switches and components are controlled or reg- ulated by the ECM. These are considered ECM Outputs. These outputs are for:
† CCD bus (+) circuits † CCD bus (-) circuits † CKP and APPS outputs to the PCM † Data link connection for DRB scan tool † Five volt sensor supply † Fuel transfer (lift) pump † Intake manifold air heater relays #1 and #2 con- † Malfunction indicator lamp (Check engine lamp) † Oil Pressure Swith/warning lamp (databus) † Fuel Control Actuator † Wait-to-start warning lamp (databus) † Fan Clutch PWM † Water-In-Fuel (WIF) warning lamp (databus)
trol circuits
(databus)
REMOVAL
The Engine Control Module (ECM) is bolted to a support bracket near the fuel filter. The support bracket mounts to the block with four capscrews and vibration isolators. A ground wire is fastened to the bracket. The other end of the wire is fastened to the engine block.
(1) Record any Diagnostic Trouble Codes (DTC’s)
found in the ECM.
DR ENGINE CONTROL MODULE (Continued)
ELECTRONIC CONTROL MODULES
8E - 5
To avoid possible voltage spike damage to either the Engine Control Module ECM, ignition key must be off, and negative battery cables must be discon- nected before unplugging ECM connectors.
(2) Disconnect both negative battery cables at both
batteries.
(3) Remove the 50–way and 60–way connector bolts at the ECM. Note: Tthe connector bolt is a female allen head. As bolt is being removed, very car- fully remove connectors from the ECM.
(4) Remove five ECM mounting bolts and remove
ECM form the vehicle (Fig. 3).
Fig.3DIESELECM
1 - ENGINE CONTROL MODULE (ECM) 2 - ECM MOUNTING BOLT 3 - 50-WAY CONNECTOR 4 - SUPPORT PLATE 5 - 60-WAY CONNECTOR
INSTALLATION
Do not apply paint to ECM. Poor ground will
result.
(1) Position ECM to ECM support bracket and install five mounting bolts. Tighten bolts to 24 N·m (18 ft. lbs.).
(2) Check pin connectors in ECM and the 50–way and 60–way connectors for corrosion or damage. Repair as necessary.
(3) Clean pins in the 50–way and 60–way electri- cal connectors with a quick-dry electrical contact cleaner.
(4) Very carefully install the 50–way and 60–way
connectors to ECM. Tighten connector allen bolts.
(5) Install both negative battery cables.
(6) Turn key to ON position. Without starting engine, slowly press throttle pedal to floor and then slowly release. This step must be done (one time) to ensure accelerator pedal position sensor calibration has been learned by ECM. If not done, possible DTC’s may be set.
(7) Use DRB scan tool to erase any stored compan-
ion DTC’s from ECM.
FRONT CONTROL MODULE DESCRIPTION
The Front Control Module (FCM) is a micro con- troller based module located in the left front corner of the engine compartment. On this model the inte- grated power module must be positioned aside in order to access the front control module. The front control module mates to the power distribution cen- ter to form the Integrated Power Module (IPM). The integrated power module connects directly to the bat- tery and provides the primary means of circuit pro- tection and power distribution for all vehicle electrical systems. The front control module controls power to some of these vehicle systems electrical and electromechanical loads based on inputs received from hard wired switch inputs and data received on the PCI bus circuit (J1850).
For information on the Integrated Power Mod- ule Refer to the Power Distribution Section of the service manual.
OPERATION
As messages are sent over the PCI bus circuit, the front control module reads these messages and con- trols power to some of the vehicles electrical systems by completing the circuit to ground (low side driver) or completing the circuit to 12 volt power (high side driver). The following functions are Controlled by the Front Control Module: † Headlamp Power with Voltage Regulation † Windshield Wiper “ON/OFF” Relay Actuation † Windshield Wiper “HI/LO” Relay Actuation † Windshield Washer Pump Motor † Fog Lamp Relay Actuation † Park Lamp Relay Actuation † Horn Relay Actuation The following inputs are Received/Monitored by † B+ Connection Detection † Power Ground † Ambient Temperature Sensing † Ignition Switch Run † Washer Fluid Level Switch † Windshield Wiper Park Switch † PCI Bus Circuit
the Front Control Module:
ELECTRONIC CONTROL MODULES
8E - 6
FRONT CONTROL MODULE (Continued) DIAGNOSIS AND TESTING - FRONT CONTROL MODULEThe front control module is a printed circuit board based module with a on-board micro-processor. The front control module interfaces with other electronic modules in the vehicle via the Programmable Com- munications Interface (PCI) data bus (J1850). In order to obtain conclusive testing the Programmable Communications Interface (PCI) data bus network and all of the electronic modules that provide inputs to, or receive outputs from the front control module must be checked. All PCI (J1850) communication faults must be resolved prior to further diagnosing any front control module related issues.
The front control module was designed to be diag- nosed with an appropriate diagnostic scan tool, such as the DRB IIIt. The most reliable, efficient, and accurate means to diagnose the front control module requires the use of a DRB IIIt scan tool and the proper Body Diagnostic Procedures manual.
Before any testing of the front control module is attempted, the battery should be fully charged and all wire harness and ground connections inspected around the affected areas on the vehicle.
REMOVAL
(1) Disconnect the positive and negative battery
cables from the battery.
(2) Partially remove the integrated power module from the engine compartment (Refer to 8 - ELECTRI- CAL/POWER DISTRIBUTION/INTEGRATED POWER MODULE - REMOVAL).
(3) Remove the front control module retaining
screws.
(4) Using both hands, pull the front control module straight from the integrated power module assembly to disconnect the 49-way electrical connector and remove the front control module from the vehicle.
INSTALLATION
(1) Install the front control module on the inte- grated power module assembly by pushing the 49-way electrical connector straight in.
(2) Install
the front
control module retaining
screws. Torque the screws to 7 in. lbs.
(3) Install the integrated power module (Refer to 8
ELECTRICAL/POWER DISTRIBUTION/INTE-GRATED POWER MODULE - INSTALLATION).
(4) Connect
the positive and negative battery
cables.
DR
HEATED SEAT MODULE DESCRIPTION
Fig.4HeatedSeatModule
1 - MOUNTING TABS (NOT USED ON DR) 2 - HEATED SEAT MODULE 3 - ELECTRICAL CONNECTOR RECEPTACLE
The heated seat module is also known as the Seat Heat Interface Module. The heated seat module (Fig. 4) is located under the drivers front seat cushion, where it is secured to a mounting bracket. The heated seat module has a single connector receptacle that allows the module to be connected to all of the required inputs and outputs through the seat wire harness.
The heated seat module is an electronic micropro- cessor controlled device designed and programmed to use inputs from the battery, the two heated seat switches and the two heated seat sensors to operate and control the heated seat elements in both front seats and the two heated seat indicator lamp Light- Emitting Diodes (LEDs) in each heated seat switch. The heated seat module is also programmed to per- form self-diagnosis of certain heated seat system functions and provide feedback of that diagnosis through the heated seat switch indicator lamps.
The heated seat module cannot be repaired. If the heated seat module is damaged or faulty, the entire module must be replaced.
OPERATION
The heated seat module operates on fused battery current received from the integrated power module. Inputs to the module include a resistor multiplexed heated seat switch request circuit for each of the two heated seat switches and the heated seat sensor inputs from the seat cushions of each front seat. In response to those inputs the heated seat module con- trols battery current feeds to the heated seat ele-
DR HEATED SEAT MODULE (Continued)
ELECTRONIC CONTROL MODULES
8E - 7
ments and sensors, and controls the ground for the heated seat switch indicator lamps.
When a heated seat switch (Driver or Passenger) is depressed a signal is received by the heated seat module, the module energizes the proper indicator LED (Low or High) in the switch by grounding the indicator lamp circuit to indicate that the heated seat system is operating. At the same time, the heated seat module energizes the selected heated seat sensor circuit and the sensor provides the module with an input the selected seat cushion.
indicating the surface temperature of
The Low heat set point is about 36° C (96.8° F), and the High heat set point is about 42° C (107.6° F). If the seat cushion surface temperature input is below the temperature set point for the selected tem- perature setting, the heated seat module energizes an N-channel Field Effect Transistor (N-FET) within the module which energizes the heated seat elements in the selected seat cushion and back. When the sen- sor input to the module indicates the correct temper- ature set point has been achieved, the module de-energizes the heated seat elements. The heated seat module will continue to cycle the N-FET as needed to maintain the selected temperature set point.
the N-FET which de-energizes
If the heated seat module detects a heated seat sensor value input that is out of range or a shorted or open heated seat element circuit, it will notify the vehicle operator or the repair technician of this con- dition by flashing the High and/or Low indicator lamps in the affected heated seat switch. Refer to Diagnosis and Testing Heated Seat System in Heated Systems for flashing LED diagnosis and test- ing procedures. Refer to Diagnosis and Testing Heated Seat Module in this section for heated seat module diagnosis and testing procedures.
DIAGNOSIS AND TESTING - HEATED SEAT MODULE
If a heated seat fails to heat and one or both of the indicator lamps on a heated seat switch flash, refer to Diagnosis and Testing Heated Seat System in Heated Seats for the location of flashing LED heated seat system diagnosis and testing procedures. If a heated seat heats but one or both indicator lamps on the heated seat switch fail to operate, test the heated to Diagnosis and Testing seat Heated Seat Switch in Heated Seats for heated seat switch diagnosis and testing procedures. If the heated seat switch checks OK, proceed as follows.
switch. Refer
(1) Check the heated seat element (Refer to 8 - SEAT
ELECTRICAL/HEATED SEATS/HEATED ELEMENT - DIAGNOSIS AND TESTING).
(2) Check the heated seat sensor (Refer to 8 - SEAT
ELECTRICAL/HEATED SENSOR - DIAGNOSIS AND TESTING).
SEATS/HEATED
(3) Check the heated seat switch (Refer to 8 - ELECTRICAL/HEATED SEATS/DRIVER HEATED SEAT SWITCH - DIAGNOSIS AND TESTING).
NOTE: Refer to Wiring for the location of complete heated seat system wiring diagrams and connector pin-out information.
(4) Using a voltmeter, backprobe the appropriate heated seat module connector, do not disconnect. Check for voltage at the appropriate pin cavities. 12v should be present. If OK go to Step 5, if Not, Repair the open or shorted voltage supply circuit as required.
(5) Using a ohmmeter, backprobe the appropriate heated seat module connector, do not disconnect. Check for proper continuity to ground on the ground pin cavities. Continuity should be present. If OK replace the heated seat module with a known good unit and retest system, if Not OK, Repair the open or shorted ground circuit as required.
REMOVAL
(1) Position the driver seat to the full rearward
and inclined position.
(2) Working under the driver front seat, remove the two heated seat module retaining screws. Due to the fact that the retaining screws are installed with the seat cushion pan removed, a small right angle screwdriver will be required to access and remove the screws.
(3) Disconnect the seat wire harness connector from the connector receptacle on the back of the heated seat module. Depress the connector retaining tab and pull straight apart.
(4) Remove the heated seat module from under the
front seat.
INSTALLATION
front seat.
(1) Position the heated seat module under the
(2) Connect the seat wire harness connector on the connector receptacle on the back of the heated seat module.
(3) Working under the driver front seat, install the
heated seat module retaining screws.
(4) Re-position the driver seat.
8E - 8
ELECTRONIC CONTROL MODULES
DR
POWERTRAIN CONTROL MODULE
DESCRIPTION
DESCRIPTION - PCM
The Powertrain Control Module (PCM) is located in the right-rear section of the engine compartment under the cowl (Fig. 5).
Two different PCM’s are used (JTEC and NGC). These can be easily identified. JTEC’s use three 32–way connectors, NGC’s use four 38–way connectors
Fig.5POWERTRAINCONTROLMODULE(PCM)
LOCATION
1 - COWL GRILL 2 - PCM 3 - COWL (RIGHT-REAR)
DESCRIPTION - MODES OF OPERATION
As input signals to the Powertrain Control Module (PCM) change, the PCM adjusts its response to the output devices. For example, the PCM must calculate different injector pulse width and ignition timing for idle than it does for wide open throttle (WOT).
The PCM will operate in two different modes:
Open Loop and Closed Loop.
During Open Loop modes, the PCM receives input signals and responds only according to preset PCM programming. Input from the oxygen (O2S) sensors is not monitored during Open Loop modes.
During Closed Loop modes, the PCM will monitor the oxygen (O2S) sensors input. This input indicates to the PCM whether or not the calculated injector pulse width results in the ideal air-fuel ratio. This ratio is 14.7 parts air-to-1 part fuel. By monitoring the exhaust oxygen content through the O2S sensor, the PCM can fine tune the injector pulse width. This is done to achieve optimum fuel economy combined with low emission engine performance.
of operation:
The fuel injection system has the following modes † Ignition switch ON † Engine start-up (crank) † Engine warm-up † Idle † Cruise † Acceleration † Deceleration † Wide open throttle (WOT) † Ignition switch OFF The ignition switch On, engine start-up (crank), engine warm-up, acceleration, deceleration and wide open throttle modes are Open Loop modes. The idle and cruise modes, (with the engine at operating tem- perature) are Closed Loop modes.
IGNITION SWITCH (KEY-ON) MODE
This is an Open Loop mode. When the fuel system is activated by the ignition switch, the following actions occur: † The PCM pre-positions the idle air control (IAC) motor.† The PCM determines atmospheric air pressure from the MAP sensor input to determine basic fuel strategy. † The PCM monitors the engine coolant tempera- ture sensor input. The PCM modifies fuel strategy based on this input. † Intake manifold air temperature sensor input is † Throttle position sensor (TPS) is monitored. † The auto shutdown (ASD) relay is energized by † The fuel pump is energized through the fuel pump relay by the PCM. The fuel pump will operate for approximately three seconds unless the engine is operating or the starter motor is engaged. † The O2S sensor heater element is energized via the ASD or O2S heater relay. The O2S sensor input is not used by the PCM to calibrate air-fuel ratio dur- ing this mode of operation.
the PCM for approximately three seconds.
monitored.
ENGINE START-UP MODE
This is an Open Loop mode. The following actions
occur when the starter motor is engaged.
The PCM receives inputs from:
DR POWERTRAIN CONTROL MODULE (Continued) † Battery voltage † Engine coolant temperature sensor † Crankshaft position sensor † Intake manifold air temperature sensor † Manifold absolute pressure (MAP) sensor † Throttle position sensor (TPS) † Camshaft position sensor signal The PCM monitors the crankshaft position sensor. If the PCM does not receive a crankshaft position sensor signal within 3 seconds of cranking the engine, it will shut down the fuel injection system.
The fuel pump is activated by the PCM through
the fuel pump relay.
Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off.
The PCM determines the proper ignition timing according to input received from the crankshaft posi- tion sensor.
ENGINE WARM-UP MODE
trans. only)
up, the PCM receives inputs from:
This is an Open Loop mode. During engine warm- † Battery voltage † Crankshaft position sensor † Engine coolant temperature sensor † Intake manifold air temperature sensor † Manifold absolute pressure (MAP) sensor † Throttle position sensor (TPS) † Camshaft position sensor signal † Park/neutral switch (gear indicator signal—auto. † Air conditioning select signal (if equipped) † Air conditioning request signal (if equipped) Based on these inputs the following occurs: † Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off. † The PCM adjusts engine idle speed through the idle air control (IAC) motor and adjusts ignition tim- ing.† The PCM operates the A/C compressor clutch through the A/C compressor clutch relay. This is done if A/C has been selected by the vehicle operator and specified pressures are met at the high and low–pres- sure A/C switches. Refer to Heating and Air Condi- tioning for additional information. † When engine has reached operating tempera- ture, the PCM will begin monitoring O2S sensor input. The system will then leave the warm-up mode and go into closed loop operation.
ELECTRONIC CONTROL MODULES
8E - 9
IDLE MODE
trans. only)
When the engine is at operating temperature, this is a Closed Loop mode. At idle speed, the PCM receives inputs from:
† Air conditioning select signal (if equipped) † Air conditioning request signal (if equipped) † Battery voltage † Crankshaft position sensor † Engine coolant temperature sensor † Intake manifold air temperature sensor † Manifold absolute pressure (MAP) sensor † Throttle position sensor (TPS) † Camshaft position sensor signal † Battery voltage † Park/neutral switch (gear indicator signal—auto. † Oxygen sensors Based on these inputs, the following occurs: † Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control injection sequence and injector pulse width by turn- ing the ground circuit to each individual injector on and off. † The PCM monitors the O2S sensor input and adjusts air-fuel ratio by varying injector pulse width. It also adjusts engine idle speed through the idle air control (IAC) motor. † The PCM adjusts ignition timing by increasing † The PCM operates the A/C compressor clutch through the A/C compressor clutch relay. This is done if A/C has been selected by the vehicle operator and specified pressures are met at the high and low–pres- sure A/C switches. Refer to Heating and Air Condi- tioning for additional information.
and decreasing spark advance.
CRUISE MODE
When the engine is at operating temperature, this is a Closed Loop mode. At cruising speed, the PCM receives inputs from:
† Air conditioning select signal (if equipped) † Air conditioning request signal (if equipped) † Battery voltage † Engine coolant temperature sensor † Crankshaft position sensor † Intake manifold air temperature sensor † Manifold absolute pressure (MAP) sensor † Throttle position sensor (TPS) † Camshaft position sensor signal † Park/neutral switch (gear indicator signal—auto. † Oxygen (O2S) sensors Based on these inputs, the following occurs: † Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then adjust
trans. only)
ELECTRONIC CONTROL MODULES
8E - 10
POWERTRAIN CONTROL MODULE (Continued)DR
the injector pulse width by turning the ground circuit to each individual injector on and off. † The PCM monitors the O2S sensor input and adjusts air-fuel ratio. It also adjusts engine idle speed through the idle air control (IAC) motor. † The PCM adjusts ignition timing by turning the ground path to the coil(s) on and off. † The PCM operates the A/C compressor clutch through the clutch relay. This happens if A/C has been selected by the vehicle operator and requested by the A/C thermostat.
ACCELERATION MODE
This is an Open Loop mode. The PCM recognizes an abrupt increase in throttle position or MAP pres- sure as a demand for increased engine output and vehicle acceleration. The PCM increases injector pulse width in response to increased throttle opening.
DECELERATION MODE
When the engine is at operating temperature, this is an Open Loop mode. During hard deceleration, the PCM receives the following inputs.
† Air conditioning select signal (if equipped) † Air conditioning request signal (if equipped) † Battery voltage † Engine coolant temperature sensor † Crankshaft position sensor † Intake manifold air temperature sensor † Manifold absolute pressure (MAP) sensor † Throttle position sensor (TPS) † Camshaft position sensor signal † Park/neutral switch (gear indicator signal—auto. † Vehicle speed If the vehicle is under hard deceleration with the proper rpm and closed throttle conditions, the PCM will ignore the oxygen sensor input signal. The PCM will enter a fuel cut-off strategy in which it will not supply a ground to the injectors. If a hard decelera- tion does not exist, the PCM will determine the proper injector pulse width and continue injection.
trans. only)
Based on the above inputs, the PCM will adjust engine idle speed through the idle air control (IAC) motor.
The PCM adjusts ignition timing by turning the
ground path to the coil on and off.
WIDE OPEN THROTTLE MODE
This is an Open Loop mode. During wide open throttle operation, the PCM receives the following inputs.
† Battery voltage † Crankshaft position sensor † Engine coolant temperature sensor † Intake manifold air temperature sensor † Manifold absolute pressure (MAP) sensor
occurs:
† Throttle position sensor (TPS) † Camshaft position sensor signal During wide open throttle conditions, the following † Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off. The PCM ignores the oxygen sensor input signal and provides a predetermined amount of addi- tional fuel. This is done by adjusting injector pulse width.† The PCM adjusts ignition timing by turning the ground path to the coil(s) on and off.
IGNITION SWITCH OFF MODE
When ignition switch is turned to OFF position, the PCM stops operating the injectors, ignition coil, ASD relay and fuel pump relay.
DESCRIPTION - 5 VOLT SUPPLIES
Two different Powertrain Control Module (PCM) five volt supply circuits are used; primary and sec- ondary.
DESCRIPTION - IGNITION CIRCUIT SENSE
This circuit ties the ignition switch to the Power-
train Control Module (PCM).
DESCRIPTION - POWER GROUNDS
The Powertrain Control Module (PCM) has 2 main grounds. Both of these grounds are referred to as power grounds. All of the high-current, noisy, electri- cal devices are connected to these grounds as well as all of the sensor returns. The sensor return comes into the sensor return circuit, passes through noise suppression, and is then connected to the power ground.
cuits for the following PCM loads:
The power ground is used to control ground cir- † Generator field winding † Fuel injectors † Ignition coil(s) † Certain relays/solenoids † Certain sensors
DESCRIPTION - SENSOR RETURN
The Sensor Return circuits are internal to the Pow-
ertrain Control Module (PCM).
Sensor Return provides a low–noise ground refer- ence for all engine control system sensors. Refer to Power Grounds for more information.
DR POWERTRAIN CONTROL MODULE (Continued) OPERATION
OPERATION - PCM
The PCM operates the fuel system. The PCM is a pre-programmed, triple microprocessor digital com- puter. It regulates ignition timing, air-fuel ratio, emission control devices, charging system, certain transmission features, speed control, air conditioning compressor clutch engagement and idle speed. The PCM can adapt its programming to meet changing operating conditions.
The PCM receives input signals from various switches and sensors. Based on these inputs, the PCM regulates various engine and vehicle operations through different system components. These compo- nents are referred to as Powertrain Control Module (PCM) Outputs. The sensors and switches that pro- vide inputs to the PCM are considered Powertrain Control Module (PCM) Inputs.
The PCM adjusts ignition timing based upon inputs it receives from sensors that react to: engine rpm, manifold absolute pressure, engine coolant tem- perature, throttle position, transmission gear selec- tion (automatic transmission), vehicle speed, power steering pump pressure, and the brake switch.
The PCM adjusts idle speed based on inputs it receives from sensors that react to: throttle position, vehicle speed, transmission gear selection, engine coolant temperature and from inputs it receives from the air conditioning clutch switch and brake switch. Based on inputs that it receives, the PCM adjusts ignition coil dwell. The PCM also adjusts the gener- ator charge rate through control of the generator field and provides speed control operation.
NOTE: PCM Inputs:
† ABS module (if equipped) † A/C request (if equipped with factory A/C) † A/C select (if equipped with factory A/C) † A/C pressure transducer † Auto shutdown (ASD) sense † Battery temperature sensor † Battery voltage † Brake switch † J1850 bus (+) circuits † J1850 bus (-) circuits † Camshaft position sensor signal † Crankshaft position sensor † Data link connection for DRB scan tool † EATX module (if equipped) † Engine coolant temperature sensor † Fuel level (through J1850 circuitry) † Generator (battery voltage) output † Ignition circuit sense (ignition switch in on/off/ crank/run position)
ELECTRONIC CONTROL MODULES
8E - 11
† Intake manifold air temperature sensor † Knock sensors (2 on 3.7L engine) † Leak detection pump (switch) sense (if equipped) † Manifold absolute pressure (MAP) sensor † Oil pressure † Oxygen sensors † Park/neutral switch (auto. trans. only) † Power ground † Power steering pressure switch (if equipped) † Sensor return † Signal ground † Speed control multiplexed single wire input † Throttle position sensor † Transfer case switch (4WD range position) † Vehicle speed signal
NOTE: PCM Outputs: † A/C clutch relay † Auto shutdown (ASD) relay † J1850 bus (+/-) circuits for: speedometer, voltme- ter, fuel gauge, oil pressure gauge/lamp, engine temp. gauge and speed control warn. lamp
† Data link connection for DRB scan tool † EGR valve control solenoid (if equipped) † EVAP canister purge solenoid † Five volt sensor supply (primary) † Five volt sensor supply (secondary) † Fuel injectors † Fuel pump relay † Generator field driver (-) † Generator field driver (+) † Idle air control (IAC) motor † Ignition coil(s) † Leak detection pump (if equipped) † Malfunction indicator lamp (Check engine lamp). † Oxygen sensor heater relays † Oxygen sensors (pulse width modulated) † Radiator cooling fan relay (pulse width modu- lated)† Speed control vacuum solenoid † Speed control vent solenoid † Tachometer (if equipped). Driven through J1850
† Transmission convertor clutch circuit. DrivenDriven through J1850 circuits.
circuits.
through J1850 circuits.
OPERATION - 5 VOLT SUPPLIES
Crankshaft Position (CKP) sensor.
Primary 5–volt supply: † supplies the required 5 volt power source to the † supplies the required 5 volt power source to the † supplies a reference voltage for the Manifold
Camshaft Position (CMP) sensor.
Absolute Pressure (MAP) sensor.
DR
ELECTRONIC CONTROL MODULES
8E - 12
POWERTRAIN CONTROL MODULE (Continued) † supplies a reference voltage for the Throttle Position Sensor (TPS) sensor. Secondary 5–volt supply: † supplies the required 5 volt power source to the oil pressure sensor. † supplies the required 5 volt power source for the Vehicle Speed Sensor (VSS) (if equipped). † supplies the 5 volt power source to the transmis- sion pressure sensor (certain automatic transmis- sions).OPERATION - IGNITION CIRCUIT SENSE
The ignition circuit sense input tells the PCM the
ignition switch has energized the ignition circuit.
Battery voltage is also supplied to the PCM through the ignition switch when the ignition is in the RUN or START position. This is referred to as the 9ignition sense9 circuit and is used to 9wake up9
the PCM. Voltage on the ignition input can be as low as 6 volts and the PCM will still function. Voltage is supplied to this circuit to power the PCM’s 8-volt reg- ulator and to allow the PCM to perform fuel, ignition and emissions control functions.REMOVAL
USE THE DRB SCAN TOOL TO REPROGRAM THE NEW POWERTRAIN CONTROL MODULE (PCM) WITH THE VEHICLES ORIGINAL IDEN- TIFICATION NUMBER (VIN) AND THE VEHI- CLES ORIGINAL MILEAGE. IF THIS STEP IS NOT DONE, A DIAGNOSTIC TROUBLE CODE (DTC) MAY BE SET.
The PCM is located in the engine compartment
attached to the dash panel (Fig. 6).
To avoid possible voltage spike damage to the PCM, ignition key must be off, and negative battery cable must be disconnected before unplugging PCM connectors.
(1) Disconnect negative battery cable at battery. (2) Remove cover over electrical connectors. Cover
snaps onto PCM.
(3) Carefully unplug the three 32–way connectors (four 38–way connectors if equipped with NGC) from PCM (Fig. 7).
(4) Remove three PCM mounting bolts (Fig. 7) and
remove PCM from vehicle.
INSTALLATION
USE THE DRB SCAN TOOL TO REPROGRAM THE NEW POWERTRAIN CONTROL MODULE (PCM) WITH THE VEHICLES ORIGINAL IDEN- TIFICATION NUMBER (VIN) AND THE VEHI- CLES ORIGINAL MILEAGE. IF THIS STEP IS NOT DONE, A DIAGNOSTIC TROUBLE CODE (DTC) MAY BE SET.
(1) Install PCM and 3 mounting bolts to vehicle.
Fig.6PCMLOCATION
1 - COWL GRILL 2 - PCM 3 - COWL (RIGHT-REAR)
Fig.7PCMREMOVAL/INSTALLATION
1 - THREE 32-WAY CONNECTORS WITH JTEC (FOUR 38-WAY CONNECTORS WITH NGC) 2 - PCM MOUNTING BRACKET 3 - PCM 4 - PCM MOUNTING SCREWS (3)
DR POWERTRAIN CONTROL MODULE (Continued)
ELECTRONIC CONTROL MODULES
8E - 13
(2) Tighten bolts. Refer to torque specifications. (3) Check pin connectors in the PCM and the three 32–way if equipped with NGC) for corrosion or damage. Also, the pin heights in connectors should all be same. Repair as necessary before installing connectors.
(four 38–way
connectors
connectors
(4) Install three 32–way connectors (four 38–way
connectors if equipped with NGC).
(5) Install cover over electrical connectors. Cover
snaps onto PCM.
(6) Install negative battery cable. (7) Use the DRB scan tool to reprogram new PCM with vehicles original Vehicle Identification Number (VIN) and original vehicle mileage.
SENTRY KEY IMMOBILIZER MODULE DESCRIPTION
The Sentry Key Immobilizer Module (SKIM) con- tains a Radio Frequency (RF) transceiver and a cen- tral processing unit, which includes the Sentry Key Immobilizer System (SKIS) program logic. The SKIS programming enables the SKIM to program and retain in memory the codes of at least two, but no more than eight electronically coded Sentry Key transponders. The SKIS programming also enables the SKIM to communicate over the Programmable Communication Interface (PCI) bus network with the Powertrain Control Module the DRBIIIt scan tool.
(PCM), and/or
OPERATION
The SKIM transmits and receives RF signals through a tuned antenna enclosed within a molded plastic ring that is integral to the SKIM housing. When the SKIM is properly installed on the steering column, the antenna ring is oriented around the igni- tion lock cylinder housing. This antenna ring must be located within eight millimeters (0.31 inches) of the Sentry Key in order to ensure proper RF communica- tion between the SKIM and the Sentry Key tran- sponder.
For added system security, each SKIM is pro- grammed with a unique “Secret Key” code and a security code. The SKIM keeps the “Secret Key” code in memory. The SKIM also sends the “Secret Key” code to each of the programmed Sentry Key tran- sponders. The security code is used by the assembly plant to access the SKIS for initialization, or by the dealer technician to access the system for service. The SKIM also stores in its memory the Vehicle Identification Number (VIN), which it learns through a PCI bus message from the PCM during initializa- tion.
The SKIM and the PCM both use software that includes a rolling code algorithm strategy, which helps to reduce the possibility of unauthorized SKIS disarming. The rolling code algorithm ensures secu- rity by preventing an override of the SKIS through the unauthorized substitution of the SKIM or the PCM. However, the use of this strategy also means that replacement of either the SKIM or the PCM units will require a system initialization procedure to restore system operation.
When the ignition switch is turned to the ON or START positions, the SKIM transmits an RF signal to excite the Sentry Key transponder. The SKIM then listens for a return RF signal from the transponder of the Sentry Key that is inserted in the ignition lock cylinder. If the SKIM receives an RF signal with valid “Secret Key” and transponder identification codes, the SKIM sends a “valid key” message to the PCM over the PCI bus. If the SKIM receives an invalid RF signal or no response, it sends “invalid key” messages to the PCM. The PCM will enable or disable engine operation based upon the status of the SKIM messages.
The SKIM also sends messages to the Instrument Cluster which controls the VTSS indicator LED. The SKIM sends messages to the Instrument Cluster to turn the LED on for about three seconds when the ignition switch is turned to the ON position as a bulb test. After completion of the bulb test, the SKIM sends bus messages to keep the LED off for a dura- tion of about one second. Then the SKIM sends mes- sages to turn the LED on or off based upon the results of the SKIS self-tests. If the VTSS indicator LED comes on and stays on after the bulb test, it indicates that the SKIM has detected a system mal- function and/or that the SKIS has become inopera- tive.
If the SKIM detects an invalid key when the igni- tion switch is turned to the ON position, it sends messages to flash the VTSS indicator LED. The SKIM can also send messages to flash the LED as an indication to the customer that the SKIS has been placed in it’s “Customer Learn” programming mode. See Sentry Key Immobilizer System Transponder Programming in this section for more information on the “Customer Learn” programming mode.
For diagnosis or initialization of the SKIM and the PCM, a DRBIIIt scan tool and the proper Powertrain Diagnostic Procedures manual are required. The SKIM cannot be repaired and, if faulty or damaged, the unit must be replaced.
ELECTRONIC CONTROL MODULES
8E - 14
SENTRY KEY IMMOBILIZER MODULE (Continued) STANDARD PROCEDURE - PCM/SKIM PROGRAMMINGNOTE: There are two procedures for transfering the secret key to the SKIM: † When ONLY the SKIM module is replaced, the secret key is transfered from the PCM to the SKIM. The ORGINAL KEYS may then be programmed to the SKIM. † When ONLY the PCM is replaced, then the secret key is transfered from the SKIM to the PCM. The ORGINAL KEYS may be used. † When BOTH the SKIM and the PCM are replaced the secret key is transferred from the SKIM to the PCM, and NEW KEYS must be pro- grammed.
NOTE: Before replacing the Powertrain Control Module (PCM) for a failed driver, control circuit, or ground circuit, be sure to check the related compo- nent/circuit integrity for failures not detected due to a double fault in the circuit. Most PCM driver/con- trol circuit failures are caused by internal compo- nent failures (i.e. relay and solenoids) and shorted circuits (i.e. pull-ups, drivers and switched circuits). These failures are difficult to detect when a double fault has occurred and only one Diagnostic Trouble Code (DTC) has set.
When a PCM (SBEC) and the Sentry Key Immobi- lizer Module (SKIM) are replaced at the same time perform the following steps in order: (1) Program the new PCM (SBEC). (2) Program the new SKIM. (3) Replace all ignition keys and program them to
the new SKIM.
PROGRAMMING THE PCM (SBEC)
The Sentry Key Immobilizer System (SKIS) Secret Key is an ID code that is unique to each SKIM. This code is programmed and stored in the SKIM, PCM and transponder chip (ignition keys). When replacing the PCM it is necessary to program the secret key into the new PCM using the DRBIIIt scan tool. Per- form the following steps to program the secret key into the PCM.
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRBIIIt scan tool and select THEFT
ALARM, SKIM then MISCELLANEOUS.
(3) Select PCM REPLACED (GAS ENGINE). (4) Enter secured access mode by entering the
vehicle four-digit PIN.
(5) Select ENTER to update PCM VIN.
DR
NOTE: If three attempts are made to enter secure access mode using an incorrect PIN, secured access mode will be locked out for one hour. To exit this lockout mode, turn the ignition to the RUN position for one hour then enter the correct PIN. (Ensure all accessories are turned OFF. Also moni- tor the battery state and connect a battery charger if necessary).
(6) Press ENTER to transfer the secret key (the
SKIM will send the secret key to the PCM).
(7) Press Page Back to get to the Select System menu and select ENGINE, MISCELLANEOUS, and SRI MEMORY CHECK.
(8) The DRBIIIt scan tool will ask, Is odometer reading between XX and XX? Select the YES or NO button on the DRB IIIt scan tool. If NO is selected, the DRBIIIt scan tool will read, Enter odometer Reading
. Enter the odometer reading from the instrument cluster and press ENTER. PROGRAMMING THE SKIM
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRBIIIt scan tool and select THEFT
ALARM, SKIM then MISCELLANEOUS.
(3) Select SKIM REPLACED (GAS ENGINE). (4) Program the vehicle four-digit PIN into SKIM. (5) Select COUNTRY CODE and enter the correct
country.
NOTE: Be sure to enter the correct country code. If the incorrect country code is programmed into the SKIM, the SKIM must be replaced.
(6) Select YES to update the VIN (the SKIM will
learn the VIN from the PCM).
(7) Press ENTER to transfer the secret key (the PCM will send the secret key information to the SKIM).
(8) Program ignition keys to the SKIM.
NOTE: If the PCM and the SKIM are replaced at the same time, all vehicle keys will need to be replaced and programmed to the new SKIM.
PROGRAMMING IGNITION KEYS TO THE SKIM
(1) Turn the ignition switch on (transmission in
park/neutral).
(2) Use the DRBIIIt scan tool and select THEFT
ALARM, SKIM then MISCELLANEOUS.
(3) Select PROGRAM IGNITION KEY’S. (4) Enter secured access mode by entering the
vehicle four-digit PIN.
DR SENTRY KEY IMMOBILIZER MODULE (Continued)
ELECTRONIC CONTROL MODULES
8E - 15
NOTE: A maximum of eight keys can be learned to each SKIM. Once a key is learned to a SKIM, it (the key) cannot be transferred to another vehicle.
(5) If ignition key programming is unsuccessful, the DRBIIIt scan tool will display one of the follow- ing messages:
(a) Programming Not Attempted - The DRBIIIt scan tool attempts to read the programmed key status and there are no keys programmed into SKIM memory.
(b) Programming Key Failed (Possible Used Key From Wrong Vehicle) - SKIM is unable to program key due to one of the following: † Faulty ignition key transponder. † Ignition key is programmed to another vehicle. (c) 8 Keys Already Learned, Programming Not
Done - SKIM transponder ID memory is full. (6) Obtain ignition keys to be programmed from
customer (8 keys maximum).
(7) Using the DRBIIIt scan tool, erase all ignition keys by selecting MISCELLANEOUS and ERASE ALL CURRENT IGN. KEYS.
(8) Program all ignition keys. Learned Key In Ignition - Ignition key transponder
ID is currently programmed in SKIM memory.
REMOVAL
cable.
(1) Disconnect and isolate the battery negative
(2) Remove the steering column upper and lower to Steering, Column, Shroud,
shrouds. Refer Removal.
(3) Disconnect the steering column wire harness connector from the Sentry Key Immobilizer Module (SKIM)
(4) Remove the screw securing the SKIM module
to the steering column (Fig. 8).
(5) Release the SKIM antenna ring retaining clips from around the ignition switch lock cylinder housing and remove the SKIM.
INSTALLATION
NOTE: If the SKIM is replaced with a new unit, a DRBIIIT scan tool MUST be used to initialize the new SKIM and to program at least two Sentry Key transponders. (Refer to 8 - ELECTRICAL/VEHICLE THEFT SECURITY - STANDARD PROCEDURE).
(1) Slide the SKIM antenna ring around the igni- tion switch lock cylinder housing and clip in place (Fig. 8).
(2) Install the retaining screw. (3) Connect the steering column wire harness con- to the Sentry Key Immobilizer Module
nector (SKIM).
Fig.8SENTRYKEYIMMOBILIZERMODULE(SKIM) 1 - SENTRY KEY IMMOBILIZER MODULE (SKIM) 2 - STEERING COLUMN 3 - SCREW 4 - WIRING HARNES
(4) Install the steering column upper and lower shrouds. Refer to Steering, Column, Shroud, Installa- tion.
(5) Connect the battery negative cable.
TRANSFER CASE CONTROL MODULE DESCRIPTION
The Transfer Case Control Module (TCCM) (Fig. 9) is a microprocessor-based assembly, controlling the 4X4 transfer case shift functions via the actuation of a shift motor and utilizing the feedback of a mode sensor assembly. Communication is via the PCI serial bus. Inputs include user selectable 4X4 modes that include 2WD, 4HI, 4LO, and Neutral. The logic and driver circuitry is contained in a molded plastic hous- ing with an embedded heat-sink and is located behind the left side of the lower instrument panel.
OPERATION
The Transfer Case Control Module (TCCM) utilizes the input from the transfer case mounted mode sen- sor, the instrument panel mounted selector switch, and the following information from the vehicle’s PCI serial bus to determine if a shift is allowed.
† Engine RPM and Vehicle Speed
ELECTRONIC CONTROL MODULES
8E - 16
TRANSFER CASE CONTROL MODULE (Continued)DR
module must receive one ignition message that denotes that the ignition is in the RUN position. † Sleep Mode will be entered, from the Reduced Power Mode, when no PCI traffic has been sensed for 20 ±1 seconds. If during Sleep Mode the module detects PCI bus traffic, it will revert to the Reduced Power mode while monitoring for ignition messages. It will remain in this state as long as there is traffic other than run or start messages, and will return to Sleep mode if the bus goes without traffic for 20 ±1
seconds.SHIFT REQUIREMENTS
Fig.9TransferCaseControlModule(TCCM)
Location
1 - INSTRUMENT PANEL 2 - TRANSFER CASE CONTROL MODULE (TCCM) 3 - TRANSFER CASE SELECTOR SWITCH
† Diagnostic Requests † Manual Transmission and Brake Applied † PRNDL † Ignition Status † ABS Messages Once the TCCM determines that a requested shift is allowed, it actuates the bi-directional shift motor as necessary to achieve the desired transfer case operating mode. The TCCM also monitors the mode sensor while controlling the shift motor to determine the status of the shift attempt.
possible power modes. These power modes are:
Several items can cause the requested shift not to be completed. If the TCCM has recognized a fault (DTC) of some variety, it will begin operation in one of four Functionality Levels. These levels are: † Level Zero - Normal Operation. † Level One - Only Mode Shifts Are Allowed. † Level Two - Only Mode Shifts and Shifts Into LOW Are Allowed (No Neutral Shifts Are Allowed). † Level Three - No Shifts Are Allowed The TCCM can also be operating in one of three † Full Power Mode is the normal operational mode of the module. This mode is achieved by normal PCI bus traffic being present and the ignition being in the RUN position. † Reduced Power Mode will be entered when the ignition has been powered off. In this state, the module will shut down power supplied to external devices, and to electronic interface inputs and out- puts. From this state the module can enter either Sleep Mode or Full Power Mode. To enter this mode, the module must receive an ignition message denot- ing that the ignition is off, or not receive any mes- sages for 5 ±0.5 seconds. To exit this mode, the
If the TCCM is in full power mode and at function- ality level zero, it uses the following criteria to deter- mine if a shift is allowed.
If any of the driver controllable conditions are not met once the shift request is recognized, the TCCM will solidly illuminate the source position’s LED and flash the desired position’s LED for all shifts except NEUTRAL. The NEUTRAL shift LED strategy will be discussed later.
(13 mph).
the TCCM.
on the PCI bus.
lowing conditions are met:
that a mode shift has been requested.
Mode shifts will be allowed regardless of trans- mission gear or vehicle speed, whenever the following conditions are met: † Front and rear wheel speed are within 21 km/hr † A change in the Selector switch state indicates † A valid mode sensor signal is being sensed by † Proper transmit/receive messages are occurring † Ignition key switch is in the RUN position. Range shifts will be allowed only if all of the fol- † Front and rear wheel speed are within 21 km/hr † A change in the Selector Switch state indicating † Transmission in NEUTRAL signal must be rec- ognized for at least 1.5 seconds ±100 msec. (Automat- ic transmissions only) † Proper transmit/receive messages are occurring † Clutch signal is recognized for 500 msec ± 50
† Vehicle speed is less than or equal to 4.8 km/hr † Ignition key switch is in the RUN position. † A valid mode sensor signal is being sensed bymsec (Manual transmissions only).
a range shift has been requested.
(3 miles per hour).
on the PCI bus.
(13 mph).
A shift into transfer case Neutral will be allowed only if all of the following conditions are met: † Front and rear wheel speed are within 21 km/hr
the TCCM.
(13 mph).
DR TRANSFER CASE CONTROL MODULE (Continued) † The recessed Neutral Selection switch has been depressed continuously for 4.0 seconds ±100 msec while all shift conditions have been continuously met. † Transmission in NEUTRAL signal recognized from the bus. (Automatic transmissions only) † Clutch signal is recognized from the bus (Manu- al transmissions only). † Proper message transmissions/receptions are occurring on the PCI bus. † Vehicle speed is less than or equal to 4.8 km/hr (3 miles per hour). † Ignition key switch is in the RUN position, engine off. † Foot Brake is applied. † A valid mode sensor signal is being sensed by the TCCM.
from the bus.(Automatic transmissions only)
A shift out of transfer case Neutral will be allowed only if all of the following conditions are met: † Front and rear wheel speed are within 21 km/hr (13 mph). † The recessed Neutral Selection switch has been depressed continuously for 1.0 seconds ±100 msec while all shift conditions have been continuously met. † Transmission in NEUTRAL signal recognized † Clutch signal is recognized from the bus (Manu- † Proper message transmissions/receptions are † Vehicle speed is less than or equal to 4.8 km/hr † Ignition key switch is in the RUN position. † Foot Brake is applied. † A valid mode sensor signal is being sensed by
occurring on the PCI bus.
al transmissions only).
(3 miles per hour).
the TCCM.
SHIFT SEQUENCES
Once all the driver controllable conditions for the requested shift have been met, the TCCM begins a shift timer with a maximum duration of 1 second per ’D’ channel transition. If the shift timer expires before the TCCM recognizes to correct mode sensor code, the shift is considered to have been blocked. The blocked shift will increment the blocked shift counter by one. The TCCM strategy for handling blocked shifts will be described later. The process the TCCM performs for the various shifts will be described first.
RANGE AND MODE SHIFTS
The process for performing all the range and mode shifts are the same. The following steps describe the process. † Allow time for Selector Switch debounce; 250
msec ±50 msec.
ELECTRONIC CONTROL MODULES
8E - 17
mode sensor code is recognized.
desired transfer case position’s LED.
† Extinguish the source gear’s LED while flashing † Engage the shift motor for a maximum of 1 sec- ond ±100 msec per ’D’ channel transition in the des- tination gear’s direction while monitoring the mode sensor channel transitions. † Disengage the shift motor when the correct † Solidly illuminate the selected gear’s LED. † Transmit a bus message that the transfer case † If the desired mode sensor code is not received after the shift timer expires (ie. a blocked or other condition exists), stop driving the motor and wait for 200 msec ±50 msec. The shift motor is then reversed in the direction back toward the source gear for up to 1.0 seconds ±100 msec. per ’D’ channel. The TCCM waits for 2.0 seconds ±50 msec. and repeats the attempt to shift to the desired position.
shift is complete.
The exception to the preceding sequence is when a shift from 4L to 2WD/AWD is requested. If 2WD/ AWD is requested from the 4L position, the transfer case is first driven to the 4H position. If the 4H posi- tion is reached, the transfer case is then driven back to the 2WD/AWD position and the shift is considered complete. If the transfer case does not reach any the 4H position, but is in the 2WD/AWD ’D’ channel, or the 2WD/AWD between gear position on the 4H side of 2WD/AWD, the shift is also considered complete.
SHIFT OUT OF NEUTRAL
shift is complete.
mode sensor code is recognized.
† Extinguish the Neutral LED. † Engage the shift motor for a maximum of 1 sec- ond ±100 msec toward the transfer case 4H mode position while monitoring the mode sensor channel transitions. † Disengage the shift motor when the correct † Extinguish the Neutral LED. † Transmit a bus message that the transfer case † If the desired mode sensor code is not received after the shift timer expires (ie. a blocked or other condition exists), stop driving the motor and wait for 200 msec ±50 msec. The shift motor is then reversed in the direction back toward the source gear for up to 1.0 seconds 100 msec. The TCCM waits for 2.0 sec- onds ±50 msec. and repeats the attempt to shift to the desired position. † When the Neutral button is released, if the 4H position is the desired position, the shift is complete. Illuminate the 4H LED. † Otherwise when the Neutral button is released, if all of the shift requirements are being met then engage the shift motor towards the desired position for 1 second ±100 msec per ’D’ channel. (if require-
ELECTRONIC CONTROL MODULES
8E - 18
TRANSFER CASE CONTROL MODULE (Continued)DR
ments for shifting are not met, illuminate the 4H LED and flash the destination LED as an indication to the driver that all of the driver controllable shift conditions are not being met). this requires another range or mode shift, begin the range/mode shift process. † If the desired mode sensor code is not received after the shift timer expires (i.e. a blocked or other condition exists), refer to the section on Blocked Shift Strategy.
If
BLOCKED SHIFT STRATEGY
When a shift is commanded, the shift motor will be driven towards its destination position, except in the case of shifting out of Neutral if 4L was selected (the transfer case will shift to the 4H position first, before proceeding to 4L). If the shift is blocked on the way to the destination, the TCCM may attempt to drive the motor back to the original position. This process will be allowed to occur 5 times. If the transfer case has reached a non-NEUTRAL ’D’ channel during the shift re-attempts, the LED for the achieved gear posi- tion is illuminated and the shift attempts are stopped. To re-attempt the desired shift, the selector switch will need to be rotated to the current position until the switch debounce timer expires then a shift will need to be requested again.
At the end of the 5th blocked attempt, the shift motor is driven towards the last known ’D’ channel position. If this motor drive allows the transfer case to reach the 2WD/AWD ’D’ channel, or the 2WD/AWD between gear position on the 4H side of 2WD/AWD, the shift is considered complete and the shift attempts are ended.
If the mode sensor is in the NEUTRAL region at the expiration of the shift timer, the TCCM will con- tinue to make the shift attempts according to the blocked shift strategy independent of whether or not the driver controlled conditions are met.
For shifts from NEUTRAL, if all 5 attempts fail to reach the desired position (which by default is 4H), the motor will be driven to stall in the direction of 4H or 4L, depending on the achieved position. If the transfer case has reached the 2WD/AWD or 4L between gear position nearest the NEUTRAL posi- tions and the shift conditions are no longer being met, the transfer case will be driven toward the cor- responding ’D’ channel. Otherwise, the transfer case will be driven in the direction opposite the last attempt with the desired target being 4H or 4L.
If the transfer case reaches the 2WD/AWD ’D’ channel when being driven in the 4H direction, then one final 1.0 second drive toward 4H is attempted. If the transfer case then reaches any of the 4H posi- tions, the shift is considered complete and the 4H LED is illuminated. If the transfer case is still the
2WD/AWD position, the shift is considered complete and the 2WD/AWD LED is illuminated.
NOTE: If after the 5th blocked shift and reversal attempt, if the transfer case position is in the NEU- TRAL region, shift attempts will continue until a non-NEUTRAL ’D’ channel is reached.
SHIFT REVERSAL TARGETS
If the shift timer expires (1 second per ’D’ channel) and the transfer case has not reached the desired position, all shifts will attempt to return to their original position with the exceptions of: † If the intended shift is going to the High rail from Low and can’t make it, but it can make the 2WD/AWD position, the motor stops at that position. The TCCM will not attempt to cross back over NEU- TRAL if it does not have to. This means that there was a block on the first attempt to go to 4H and the transfer case has made it through NEUTRAL to a known good position, then the motor will go back only to the 2WD/4WD position and execute the remainder of the attempts from there. † For shifts out of NEUTRAL, any time a shift is commanded out of NEUTRAL, the system needs to get out. The TCCM should never go to NEUTRAL unless the driver is commanding it and all required conditions are being met
ENCODER DRIFT CORRECTION
Whenever a shift is completed, the TCCM stores the position in memory as the transfer case’s intended position. The TCCM continuously monitors the mode sensor and if the mode sensor drifts toward into a NEUTRAL region sensor position for 2.0 sec- onds, the TCCM will perform a motor drive to correct the drift. The transfer case will be driven toward the intended position for 1.0 seconds 100 msec. The TCCM will wait for 2.0 seconds ±50 msec. and repeat the attempt to shift to the desired position. This will continue until the intended position is reached.
SHIFT MOTOR BRAKING
Two modes of shift motor braking are employed to improve shift performance, static and dynamic. Static shift motor braking is utilized under the following conditions: † Whenever the transfer case is in the 2WD/AWD † Whenever an invalid mode sensor
or 4L ’D’ channel position.
code is
present.
Static motor braking is achieved by applying +12V
on both shift motor wires.
NOTE: Static Shift Motor Braking is independent of ignition key position.
DR TRANSFER CASE CONTROL MODULE (Continued) SHIFT ATTEMPT LIMIT
ELECTRONIC CONTROL MODULES
8E - 19
To protect the transfer case system, the TCCM will impose a limit on the number of shifts that can occur over a calibrated time period. The system will monitor the number of ’D’ channel segment transitions that occur in any 30 second time period. If the number of segment transitions is 30 or greater, the system will go into a default mode. The default mode of operation for shifting is that the number of allowed ’D’ channel tran- sitions permitted to occur will be 3 over each 15 second ±100 msec calibrated window of time. After 5 minutes ±100 msec, the motor can be assumed to have cooled down and the system will revert to normal operation. The following rules also apply to the shift limit: † The attempt limit will not prevent shifts coming out of NEUTRAL, they will be allowed regardless of the counter/timer. † Any shift that is in progress when the counter reaches a maximum count in time will be allowed to complete before the default mode is entered. D-chan- nel transitions during this period will not be counted towards the default mode limit. † A block, regardless of the direction, whether towards destination or back towards reversal target (shift timer expiring), will count as a value of 2 tran- sitions towards the 30 segment transitions to go into default mode as defined above. Current attempt limit values are 30 transitions in 30 seconds and default mode values are 3 transitions every 15 seconds for 5
minutes.TRANSMISSION CONTROL MODULE DESCRIPTION
The Transmission Control Module (TCM) (Fig. 10) may be sub-module within the Powertrain Control Module (PCM) or a standalone module, depending on the vehicle engine. The PCM, and TCM when equipped, is located at the right rear of the engine compartment, near the right inner fender.
OPERATION
The Transmission Control Module (TCM) controls all electronic operations of the transmission. The TCM receives information regarding vehicle opera- tion from both direct and indirect inputs, and selects the operational mode of the transmission. Direct inputs are hardwired to, and used specifically by the TCM. Indirect inputs are shared with the TCM via the vehicle communication bus. Some examples of direct inputs to the TCM are: † Battery (B+) voltage † Ignition “ON” voltage † Transmission Control Relay (Switched B+)
Fig.10PCM/TCMLocation
1 - RIGHT FENDER 2 - TRANSMISSION CONTROL MODULE 3 - POWERTRAIN CONTROL MODULE
† Throttle Position Sensor † Crankshaft Position Sensor † Transmission Range Sensor † Pressure Switches † Transmission Temperature Sensor † Input Shaft Speed Sensor † Output Shaft Speed Sensor † Line Pressure Sensor Some examples of indirect inputs to the TCM are: † Engine/Body Identification † Manifold Pressure † Target Idle † Torque Reduction Confirmation † Engine Coolant Temperature † Ambient/Battery Temperature † DRBIIIt Scan Tool Communication Based on the information received from these var- ious inputs, the TCM determines the appropriate shift schedule and shift points, depending on the present operating conditions and driver demand. This is possible through the control of various direct and indirect outputs. Some examples of TCM direct outputs are: † Transmission Control Relay † Solenoids † Torque Reduction Request Some examples of TCM indirect outputs are: † Transmission Temperature (to PCM) † PRNDL Position (to BCM) In addition to monitoring inputs and controlling outputs, the TCM has other important responsibili- ties and functions: † Storing and maintaining Clutch Volume Indexes (CVI)† Storing and selecting appropriate Shift Schedules † System self-diagnostics † Diagnostic capabilities (with DRBIIIt scan tool)
DR
ELECTRONIC CONTROL MODULES
8E - 20
TRANSMISSION CONTROL MODULE (Continued)NOTE: If the TCM has been replaced, the “Quick Learn Procedure” must be performed. (Refer to 8 - ELECTRI- CAL/ELECTRONIC CONTROL MODULES/TRANSMIS- SION CONTROL MODULE - STANDARD PROCEDURE)
BATTERY FEED
A fused, direct battery feed to the TCM is used for continuous power. This battery voltage is necessary to retain memory in the TCM. When the battery (B+) is disconnected, this memory is lost. When the bat- tery (B+) is restored, this memory loss is detected by the TCM and a Diagnostic Trouble Code (DTC) is set.
CLUTCH VOLUME INDEXES (CVI)
An important function of the TCM is to monitor Clutch Volume Indexes (CVI). CVIs represent the vol- ume of fluid needed to compress a clutch pack.
The TCM monitors gear ratio changes by monitor- ing the Input and Output Speed Sensors. The Input, or Turbine Speed Sensor sends an electrical signal to the TCM that represents input shaft rpm. The Out- put Speed Sensor provides the TCM with output shaft speed information.
By comparing the two inputs, the TCM can deter- mine transmission gear position. This is important to the CVI calculation because the TCM determines CVIs by monitoring how long it takes for a gear change to occur (Fig. 11).
Gear ratios can be determined by using the DRBIIIt Scan Tool and reading the Input/Output Speed Sensor values in the “Monitors” display. Gear ratio can be obtained by dividing the Input Speed Sensor value by the Output Speed Sensor value.
For example, if the input shaft is rotating at 1000
rpm and the output shaft is rotating at 500 rpm, then the TCM can determine that the gear ratio is 2:1. In direct drive (3rd gear), the gear ratio changes to 1:1. The gear ratio changes as clutches are applied and released. By monitoring the length of time it takes for the gear ratio to change following a shift request, the TCM can determine the volume of fluid used to apply or release a friction element.The volume of transmission fluid needed to apply the friction elements are continuously updated for adaptive controls. As friction material wears, the vol- ume of fluid need to apply the element increases.
Certain mechanical problems within the input clutch assembly can cause inadequate or out-of-range element volumes. Also, defective Input/Output Speed Sensors and wiring can cause these conditions. The following chart identifies the appropriate clutch vol- umes and when they are monitored/updated:
Fig.11ExampleofCVICalculation
1 - OUTPUT SPEED SENSOR 2 - OUTPUT SHAFT 3 - CLUTCH PACK 4 - SEPARATOR PLATE 5 - FRICTION DISCS 6 - INPUT SHAFT 7 - INPUT SPEED SENSOR 8 - PISTON AND SEAL
CLUTCH VOLUMES
Clutch
When Updated
Proper Clutch
Volume
L/R
2C
OD 4C
UD
2-1 or 3-1
downshift3-2 kickdown
shift
2-3 upshift 3-4 upshift
4-3 kickdown
shift
45 to 134
25 to 85
30 to 100
30 to 8530 to 100
SHIFT SCHEDULES
As mentioned earlier, the TCM has programming that allows it to select a variety of shift schedules. Shift schedule selection is dependent on the following: † Shift lever position † Throttle position † Engine load † Fluid temperature † Software level As driving conditions change, the TCM appropri- ately adjusts the shift schedule. Refer to the follow- ing chart to determine the appropriate operation expected, depending on driving conditions.
DR TRANSMISSION CONTROL MODULE (Continued)
ELECTRONIC CONTROL MODULES
8E - 21
Schedule
Condition
Expected Operation
Extreme Cold
Oil temperature below -16° F
Super Cold
Oil temperature between -12° F and 10° F
Cold
Warm
Hot
Overheat
Oil temperature between 10° F and 36° F
Oil temperature between 40° F and 80° F
Oil temperature between 80° F and 240° F
Oil temperature above 240° F or engine coolant temperature above 244° F
-Park, Reverse, Neutral and 1st and 3rd gear only in D position, 2nd gear only in Manual 2 or L -No EMCC - Delayed 2-3 upshift - Delayed 3-4 upshift - Early 4-3 coastdown shift - High speed 4-2, 3-2, 2-1 kickdown shifts are prevented -Shifts at high throttle openings willl be early. - No EMCC -Shift schedule is the same as Super Cold except that the 2-3
upshifts are not delayed. - Normal operation (upshift, kickdowns, and coastdowns) - No EMCC - Normal operation (upshift, kickdowns, and coastdowns) - Normal EMCC operation - Delayed 2-3 upshift - Delayed 3-4 upshift - 3rd gear FEMCC from 30-48 mph - 3rd gear PEMCC above 35 mph - Above 25 mph the torque converter will not unlock unless the throttle is closed or if a wide open throttle 2nd PEMCC to 1 kickdown is madeSTANDARD PROCEDURE
STANDARD PROCEDURE - TCM QUICK LEARN The quick learn procedure requires the use of the
DRBt scan tool.
This program allows the electronic transmission system to recalibrate itself. This will provide the proper transmission operation. The quick learn pro- cedure should be performed if any of the following procedures are performed:
† Transmission Assembly Replacement † Transmission Control Module Replacement † Solenoid Pack Replacement † Clutch Plate and/or Seal Replacement † Valve Body Replacement or Recondition To perform the Quick Learn Procedure, the follow- † The brakes must be applied † The engine speed must be above 500 rpm † The throttle angle (TPS) must be less than 3
degreesing conditions must be met:
prompted to shift to overdrive
† The shift lever position must stay in PARK until † The shift lever position must stay in overdrive after the Shift to Overdrive prompt until the DRBt indicates the procedure is complete † The calculated oil temperature must be above
60° and below 200°
STANDARD PROCEDURE - DRIVE LEARN
When a transmission is repaired and a Quick Learn procedure has been performed on the Trans- mission Control Module (TCM), the following Drive Learn procedure can be performed to fine tune any shifts which are particularly objectionable.
NOTE: It is not necessary to perform the complete Drive Learn procedure every time the TCM is Quick Learned. Perform only the portions which target the objectionable shift.
ELECTRONIC CONTROL MODULES
8E - 22
TRANSMISSION CONTROL MODULE (Continued) LEARN A SMOOTH 1ST NEUTRAL TO DRIVE SHIFT Perform this procedure only if the complaint is for a delayed or harsh shift the first time the transmis- sion is put into gear after the vehicle is allowed to set with the engine not running for at least 10 min- utes. Use the following steps to have the TCM learn the 1st N-D UD CVI.DR
itor Norm N-D UD CVI volume until the value stabi- lizes. The value will change during the N-D shift. This is normal since the UD value is different for the N-D shift then the normal value shown which is used for 4-3 coastdown and kickdowns. Perform repeated shifts in this temperature range until the Norm N-D UD CVI value stabilizes and the N-D shifts become smooth.
NOTE: The transmission oil temperature must be between 80 - 110°F (27 - 43°C).
(1) Start the engine only when the engine and ignition have been off for at least ten (10) minutes. (2) With the vehicle at a stop and the service brake applied, record the 1st N-D UD CVI while per- forming a Neutral to Drive shift. The 1st N-D UD CVI accounts for air entrapment in the UD clutch that may occur after the engine has been off for a period of time.
(3) Repeat Step 1 and Step 2 until the recorded 1st
N-D UD CVI value stabilizes.
NOTE: It is important that this procedure be per- formed when the transmission temperature is between 80 - 110°F (27 - 43°C). If this procedure takes too long to complete fully for the allowed transmission oil temperature, the vehicle may be returned to the customer with an explanation that the shift will improve daily during normal vehicle usage. The TCM also learns at higher oil tempera- tures, but these values (line pressure correction values) are not available for viewing on the DRBT III.
LEARN A SMOOTH NEUTRAL TO DRIVE GARAGE SHIFT
Perform this procedure if the complaint is for a delayed or harsh shift when the transmission is put into gear after the vehicle has had its first shift. Use the following steps to have the TCM learn the Norm N-D UD CVI.
NOTE: The transmission oil temperature must be between 80 - 110°F (27 - 43°C) to learn the UD CVI. Additional learning occurs at temperatures as low as 0°F and as high as 200°F. This procedure may be performed at any temperature that experiences poor shift quality. Although the UD CVI may not change, shift quality should improve.
(1) Start the vehicle engine and shift to drive. (2) Move the vehicle forward to a speed of at least 16 km/h (10 MPH) and come to a stop. This ensures no air is present in the UD hydraulic circuit.
(3) Perform repeated N-D shifts at a stop while pausing in Neutral for at least 2-3 seconds and mon-
LEARN THE 1ST 2-3 SHIFT AFTER A RESTART OR SHIFT TO REVERSE
Use the following steps to have the TCM learn the
1st 2-3 shift OD CVI.
NOTE: The transmission oil temperature must be above 80°F (27°C).
(1) With the vehicle engine running, select reverse
gear for over 2 seconds.
(2) Shift the transmission to Drive and accelerate the vehicle from a stop at a steady 15 degree throttle opening and perform a 2-3 shift while noting the 1st 2-3 OD CVI.
(3) Repeat Step 1 and Step 2 until the 1st 2-3
upshift becomes smooth and the 1st 2-3 OD CVI sta- bilizes.LEARN A SMOOTH 2-3 AND 3-4 UPSHIFT
NOTE: The transmission oil temperature must be above 110°F (43°C).
Use the following steps to have the TCM learn the
OD and 4C CVI’s.
(1) Accelerate the vehicle from a stop at a steady 15 degree throttle opening and perform multiple 1-2, 2-3, and 3-4 upshifts. The 2nd 2-3 shift following a restart or shift to reverse will be shown during the shift as a value between the 1st 2-3 OD CVI and the normal OD CVI. Updates to the normal OD CVI will occur after the 2nd shift into 3rd gear, following a restart or shift to reverse.
(2) Repeat Step 1 until the 2-3 and 3-4 shifts become smooth and the OD and 4C CVI become sta- ble.
LEARN A SMOOTH 4-3 COASTDOWN AND PART THROTTLE 4-3 KICKDOWN
NOTE: The transmission oil temperature must be above 110°F (43°C).
Use the following steps to have the TCM learn the
UD shift volume.
(1) At a vehicle speed between 64-97 km/h (40-60
MPH), perform repeated 4-3 kickdown shifts.
DR TRANSMISSION CONTROL MODULE (Continued)
ELECTRONIC CONTROL MODULES
8E - 23
(2) Repeat Step 1 until the UD volume becomes
somewhat stable and the shift becomes smooth.
LEARN A SMOOTH 1-2 UPSHIFT AND 3-2
KICKDOWNUse the following steps to have the TCM learn the
2C shift volume.
NOTE: The transmission oil temperature must be above 110°F (43°C).
(1) With a vehicle speed below 48 km/h (30 MPH) and the transmission in 3rd gear, perform multiple 3-2 kickdowns.
(2) Repeat Step 1 until the 3-2 kickdowns become
smooth and the 2C CVI becomes stable.
LEARN A SMOOTH MANUAL 2-1 PULLDOWN SHIFT AS WELL AS A NEUTRAL TO REVERSE SHIFT
NOTE: The transmission oil temperature must be above 110°F (43°C).
Use the following steps to have the TCM learn the
LR volume.
(1) With the vehicle speed around 40-48 km/h (25-30 MPH) in Manual 2nd, perform manual pull- downs to Low or 1st gear at closed throttle.
(2) Repeat Step 1 until the LR CVI becomes stable
and the manual 2-1 becomes smooth.
LEARN A SMOOTH NEUTRAL TO REVERSE SHIFT
NOTE: The transmission oil temperature must be above 110°F (43°C).
(1) With the vehicle at a stop, perform Neutral to Reverse shifts until the shift is smooth. An unlearned Neutral to Reverse shift may be harsh or exhibit a double bump.
(2) If any of the shifts are still not smooth after the clutch volume stabilizes, an internal transmis- sion problem may be present.
LEARN A SMOOTH 4-5 UPSHIFT
NOTE: The transmission oil temperature must be above 110°F (43°C).
Use the following steps to have the TCM learn the
Alt 2C CVI.
(1) Accelerate
through 88 km/h (55mph) at a steady 10-15 degree throttle opening and perform multiple 4-5 upshifts.
vehicle
the
(2) Repeat Step 1 until
the 4-5 shift become smooth and theAlt 2C CVI become stable. There is a separate 2C volume used and learned for 4-5 shifts, 2CA. It is independent of the 2C CVI learned on 3-2
kickdowns.DR
