Electronic Control Modules - Service Information: Other Dodge Dakota III

PCM/SKREEM PROGRAMMING

Note. Before replacing the Powertrain Control Module (PCM), be certain to check the related component/circuit integrity for failures not detected due to a double fault in the circuit. Most PCM driver/control circuit failures are caused by internal component failures (i.e. relays 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 DTC has been set.

When a Powertrain Control Module (PCM) and the Sentry Key REmote Entry Module (SKREEM) on vehicles equipped with the Sentry Key Immobilizer System (SKIS) are replaced at the same time, perform the following steps in order

1. Program the new PCM.
2. Program the new SKREEM (also sometimes referred to as the Wireless Control Module or WCM).
3. Replace all ignition keys and program them into the new SKREEM/WCM.

PROGRAMMING THE PCM/SKREEM

The SKIS Secret Key is an ID code that is unique to each SKREEM/WCM. This code is programmed and stored in the SKREEM/WCM, the PCM, and each ignition key transponder chip. When the PCM or SKREEM/WCM is replaced, it is necessary to program the Secret Key into the new module using a diagnostic scan tool. Follow the programming steps outlined in the diagnostic scan tool for "PCM Replaced" or "WCM Replaced" under "Miscellaneous Functions" for the "WCM/Wireless Control Module" menu item as appropriate.

Note. Be certain to enter the correct country code for the SKREEM/WCM. If the incorrect country code is programmed into the SKREEM, it cannot be changed and the SKREEM must be replaced.

Note. If the PCM and the SKREEM/WCM are replaced at the same time, all vehicle ignition keys will need to be replaced and new keys programmed into the new SKREEM/WCM.

Note. Programming the PCM or SKREEM is done using a diagnostic scan tool and a PIN to enter secure access mode. If three attempts are made to enter secure access mode using an incorrect PIN, secure 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 monitor the battery state and connect a battery charger if necessary).

PROGRAMMING IGNITION KEYS TO THE SKREEM

Each ignition key transponder also has a unique ID code that is assigned at the time the key is manufactured. When a key is programmed into the SKREEM/WCM, the transponder ID code is learned by the module and the transponder acquires the unique Secret Key ID code from the SKREEM/WCM. To program ignition keys into the SKREEM/WCM, follow the programming steps outlined in the diagnostic scan tool for "Program Ignition Keys or Key FOBs" under "Miscellaneous Functions" for the "WCM/Wireless Control Module" menu item.

Note. A maximum of eight keys can be learned to each SKREEM. Once a key is learned to a SKREEM, that key has acquired the Secret Key for that SKREEM and cannot be transferred to any other SKREEM or vehicle.

If ignition key programming is unsuccessful, the scan tool will display one of the following error messages

1. Programming Not Attempted - The scan tool attempts to read the programmed key status and there are no keys programmed into SKREEM memory.
2. Programming Key Failed (Possible Used Key From Wrong Vehicle) - SKREEM is unable to program an ignition key transponder due to one of the following: The ignition key transponder is faulty. The ignition key transponder is or has been already programmed to another vehicle.
3. 8 Keys Already Learned, Programming Not Done - The SKREEM transponder ID memory is full.
4. Learned Key In Ignition - The ID for the ignition key transponder currently in the ignition lock cylinder is already programmed into SKREEM memory.

ABM INPUTS

The ABM continuously monitors the speed of the vehicle by monitoring signals generated by the wheel speed sensors. The ABM determines a wheel locking tendency when it recognizes the axle is decelerating too rapidly. The ABM monitors the following inputs to determine when a wheel locking tendency may exists

1. Wheel Speed Sensors
2. Brake Lamp Switch
3. Brake Fluid Level Sensor
4. G-Sensor
5. 4WD Switch (If equipped)

ABM OUTPUTS

The ABM requests the following outputs for antilock braking and brake warning information from the CCN via CAN C Bus

1. ABS Warning Lamp
2. Brake Warning Lamp

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

1. The PCM pre-positions the idle air control (IAC) motor.
2. The PCM determines atmospheric air pressure from the MAP sensor input to determine basic fuel strategy.
3. The PCM monitors the engine coolant temperature sensor input. The PCM modifies fuel strategy based on this input.
4. Intake manifold air temperature sensor input is monitored.
5. Throttle position sensor (TPS) is monitored.
6. The auto shutdown (ASD) relay is energized by the PCM for approximately three seconds.
7. 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.
8. The O2S sensor heater element is energized via the ASD relay. The O2S sensor input is not used by the PCM to calibrate air-fuel ratio during this mode of operation.

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

1. Battery voltage
2. Engine coolant temperature sensor
3. Crankshaft position sensor
4. Intake manifold air temperature sensor
5. Manifold absolute pressure (MAP) sensor
6. Throttle position sensor (TPS)
7. Starter motor relay
8. 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 position sensor.

ENGINE WARM-UP MODE

This is an Open Loop mode. During engine warm-up, the PCM receives inputs from

1. Battery voltage
2. Crankshaft position sensor
3. Engine coolant temperature sensor
4. Intake manifold air temperature sensor
5. Manifold absolute pressure (MAP) sensor
6. Throttle position sensor (TPS)
7. Camshaft position sensor signal
8. Park/neutral switch (gear indicator signal-auto. trans. only)
9. Air conditioning select signal (if equipped)
10. Air conditioning request signal (if equipped)

Based on these inputs the following occurs

1. 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.
2. The PCM adjusts engine idle speed through the idle air control (IAC) motor and adjusts ignition timing.
3. The PCM operates the A/C compressor clutch through the clutch relay. This is done if A/C has been selected by the vehicle operator and requested by the A/C thermostat.
4. When engine has reached operating temperature, the PCM will begin monitoring O2S sensor input. The system will then leave the warm-up mode and go into closed loop operation.

IDLE MODE

When the engine is at operating temperature, this is a Closed Loop mode. At idle speed, the PCM receives inputs from

1. Air conditioning select signal (if equipped)
2. Air conditioning request signal (if equipped)
3. Battery voltage
4. Crankshaft position sensor
5. Engine coolant temperature sensor
6. Intake manifold air temperature sensor
7. Manifold absolute pressure (MAP) sensor
8. Throttle position sensor (TPS)
9. Camshaft position sensor signal
10. Battery voltage
11. Park/neutral switch (gear indicator signal-auto. trans. only)
12. Oxygen sensors

Based on these inputs, the following occurs

1. 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 turning the ground circuit to each individual injector on and off.
2. 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.
3. The PCM adjusts ignition timing by increasing and decreasing spark advance.
4. 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.

CRUISE MODE

When the engine is at operating temperature, this is a Closed Loop mode. At cruising speed, the PCM receives inputs from

1. Air conditioning select signal (if equipped)
2. Air conditioning request signal (if equipped)
3. Battery voltage
4. Engine coolant temperature sensor
5. Crankshaft position sensor
6. Intake manifold air temperature sensor
7. Manifold absolute pressure (MAP) sensor
8. Throttle position sensor (TPS)
9. Camshaft position sensor signal
10. Park/neutral switch (gear indicator signal-auto. trans. only)
11. Oxygen (O2S) sensors

Based on these inputs, the following occurs

1. Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then adjust the injector pulse width by turning the ground circuit to each individual injector on and off.
2. 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.
3. The PCM adjusts ignition timing by turning the ground path to the coil on and off.
4. 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 pressure 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.

1. Air conditioning select signal (if equipped)
2. Air conditioning request signal (if equipped)
3. Battery voltage
4. Engine coolant temperature sensor
5. Crankshaft position sensor
6. Intake manifold air temperature sensor
7. Manifold absolute pressure (MAP) sensor
8. Throttle position sensor (TPS)
9. Camshaft position sensor signal
10. Park/neutral switch (gear indicator signal-auto. trans. only)
11. Vehicle speed sensor

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 deceleration does not exist, the PCM will determine the proper injector pulse width and continue injection.

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.

1. Battery voltage
2. Crankshaft position sensor
3. Engine coolant temperature sensor
4. Intake manifold air temperature sensor
5. Manifold absolute pressure (MAP) sensor
6. Throttle position sensor (TPS)
7. Camshaft position sensor signal

During wide open throttle conditions, the following occurs

1. 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 additional fuel. This is done by adjusting injector pulse width.
2. The PCM adjusts ignition timing by turning the ground path to the coil 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.

SHIFT REQUIREMENTS

If the FCM is in full power mode and at functionality level zero, it uses the following criteria to determine if a shift is allowed.

If any of the driver controllable conditions are not met once the shift request is recognized, the FCM may illuminate one or more of the 4WD system message icons in the instrument cluster display.

Mode shifts will be allowed regardless of transmission gear or vehicle speed, whenever the following conditions are met

1. Ignition key switch is in the RUN position.
2. Front and rear wheel speed are within 21 km/hr (13 mph).
3. A change in the Selector switch state indicates that a mode shift has been requested.
4. A valid mode sensor signal is being sensed by the FCM.
5. Proper transmit/receive messages are occurring on the CAN bus.
6. An Anti-lock Brake System (ABS) event is not in progress.

Range shifts will be allowed only if all of the following conditions are met

1. Ignition key switch is in the RUN position.
2. Front and rear wheel speed are within 21 km/hr (13 mph).
3. A change in the Selector Switch state indicating a range shift has been requested.
4. Transmission in NEUTRAL signal must be recognized for at least 1.5 seconds +/-100 msec. (Automatic transmissions only)
5. Proper transmit/receive messages are occurring on the CAN bus.
6. Clutch signal is recognized for 500 msec +/- 50 msec (Manual transmissions only).
7. Vehicle speed is less than or equal to 4.8 km/hr (3 miles per hour).
8. A valid mode sensor signal is being sensed by the FCM.
9. An Anti-lock Brake System (ABS) event is not in progress.

A shift into transfer case Neutral will be allowed only if all of the following conditions are met

1. Ignition key switch is in the RUN position, engine off.
2. Front and rear wheel speed are within 21 km/hr (13 mph).
3. The recessed Neutral Selection switch has been depressed continuously for 4.0 seconds +/-100 msec while all shift conditions have been continuously met.
4. Transmission in NEUTRAL signal recognized from the bus. (Automatic transmissions only)
5. Clutch signal is recognized from the bus (Manual transmissions only).
6. Proper message transmissions/receptions are occurring on the CAN bus.
7. Vehicle speed is less than or equal to 4.8 km/hr (3 miles per hour).
8. Foot Brake is applied.
9. A valid mode sensor signal is being sensed by the FCM.
10. An Anti-lock Brake System (ABS) event is not in progress.

A shift out of transfer case Neutral will be allowed only if all of the following conditions are met

1. Ignition key switch is in the RUN position.
2. Front and rear wheel speed are within 21 km/hr (13 mph).
3. The recessed Neutral Selection switch has been depressed continuously for 1.0 seconds +/-100 msec while all shift conditions have been continuously met.
4. Transmission in NEUTRAL signal recognized from the bus. (Automatic transmissions only)
5. Clutch signal is recognized from the bus (Manual transmissions only).
6. Proper message transmissions/receptions are occurring on the CAN bus.
7. Vehicle speed is less than or equal to 4.8 km/hr (3 miles per hour).
8. A valid mode sensor signal is being sensed by the FCM.
9. An Anti-lock Brake System (ABS) event is not in progress.

LAMP STRATEGY

The following strategy for the FCM controlled transfer case system uses the instrument cluster VF display's 4LOCK, 4LO, Service 4WD, and Mode Switch Transfer Case Neutral LED. Flashing any of the lamps or LED is accomplished at a 2Hz rate.

Note. There is no lamp for the AWD position. If no 4WD system message icons are illuminated in the instrument cluster, the operator is to assume that the transfer case is in the AWD position.

1. AWD to 4LO - Successful shifts will flash 4LO during a shift, then after the 4LO position has been met, display the 4LO lamp solid. In the blocked condition, flash the 4LO lamp during the 5 Phase 1 shift attempts. After 5 unsuccessful attempts, the transfer case remains in AWD and no lamps are illuminated. When shift conditions are not met, no shift attempts are made and the 4LO lamp is flashing.
2. AWD to 4LOCK - Successful shifts will flash 4LOCK during a shift, then after the 4LOCK position has been met, display the 4LOCK lamp solid. In the blocked condition, flash the 4LOCK lamp during the 5 Phase 1 shift attempts. After 5 unsuccessful attempts, the transfer case remains in AWD and no lamps are illuminated. When shift conditions are not met, no shift attempts are made and the 4LOCK lamp is flashing.
3. 4LOCK to 4LO - Successful shifts will turn off the 4LOCK lamp and flash 4LO during a shift, then after the 4LO position has been met, display the 4LO lamp solid. In the blocked condition, turn off 4LOCK and flash the 4LO lamp during the 5 Phase 1 shift attempts. After 5 unsuccessful attempts, the transfer case remains in 4LOCK and the 4LOCK lamp turns on solid. When shift conditions are not met, the 4LOCK lamp remains illuminated solid and the 4LO lamp is flashing.
4. 4LOCK to AWD - Successful shifts will flash the 4LOCK lamp during a shift, then after the AWD position has been met, turn off the 4LOCK lamp. In the blocked condition, flash the 4LOCK lamp during the 5 Phase 1 shift attempts. After 5 unsuccessful attempts, the transfer case remains in 4LOCK and the 4LOCK lamp turns on solid. When shift conditions are not met, no shift attempts are made and the 4LOCK lamp is flashing.
5. 4LO to AWD - Successful shifts will flash the 4LO lamp during a shift, then after the AWD position has been met, turn off the 4LO lamp. In the blocked condition, flash the 4LO lamp during the 5 Phase 1 shift attempts. After 5 unsuccessful attempts, the transfer case remains in 4LO and the 4LO lamp turns on solid. When shift conditions are not met, no shift attempts are made and the 4LO lamp is flashing.
6. 4LO to 4LOCK - Successful shifts will turn off the 4LO lamp and flash 4LOCK during a shift, then after the 4LOCK position has been met, display the 4LOCK lamp solid. In the blocked condition, turn off 4LO and flash the 4LOCK lamp during the 5 Phase 1 shift attempts. After 5 unsuccessful attempts, the transfer case remains in 4LO and the 4LO lamp turns on solid. When shift conditions are not met, the 4LO lamp remains illuminated solid and 4LOCK is flashing.
7. AWD to NEUTRAL - Successful shifts have no lamps illuminated, then after the NEUTRAL position has been met, display the NEUTRAL LED solid. In the blocked condition, no lamps are illuminated during the 5 Phase 1 attempts. After 5 unsuccessful attempts, the transfer case remains in AWD and no lamps are illuminated. When shift conditions are not met, flash the NEUTRAL lamp while the push button is depressed.
8. 4LOCK to NEUTRAL - Successful shifts have no lamps illuminated, then after the NEUTRAL position has been met, display the NEUTRAL LED solid. In the blocked condition, no lamps are illuminated during the 5 Phase 1 attempts. After 5 unsuccessful attempts, the transfer case remains in 4LOCK and the 4LOCK lamp is illuminated. When shift conditions are not met, flash the NEUTRAL lamp while the push button is depressed.
9. 4LO to NEUTRAL - Successful shifts have no lamps illuminated, then after the NEUTRAL position has been met, display the NEUTRAL LED solid. In the blocked condition, no lamps are illuminated during the 5 Phase 1 attempts. After 5 unsuccessful attempts, the transfer case remains in 4LO and the 4LO lamp is illuminated. When shift conditions are not met, flash the NEUTRAL lamp while the push button is depressed.
10. NEUTRAL to AWD - Successful shifts have no lamps illuminated, then after the AWD position has been met, no lamps are illuminated. In the blocked condition, no lamps are illuminated during the 5 Phase 1 attempts. After 5 unsuccessful attempts, Phase 2 shifting will continue until the transfer case is in the AWD or 4LO position. If the final position is AWD, no lamp is illuminated, if the final position is 4LO, illuminate the 4LO lamp. When shift conditions are not met, flash the 4LOCK and 4LO lamps and the NEUTRAL LED remains solid while the push button is depressed
11. Neutral to 4LOCK - Successful shifts will flash the 4LOCK lamp during a shift, then after the 4LOCK position has been met, display the 4LOCK lamp solid. In a blocked condition, the 4LOCK lamp will flash during the 5 Phase 1 attempts. After 5 unsuccessful attempts, continue to flash the 4LOCK, Phase 2 shifting will continue until the transfer case is in the AWD or 4LO position. If the final position is AWD, turn off the 4LOCK lamp, if the final position is 4LO, illuminate the 4LO lamp. When shift conditions are not met, flash the 4LOCK and 4LO lamps and the NEUTRAL LED remains solid while the push button is depressed.
12. NEUTRAL to 4LO - Successful shifts will flash the 4LO lamp during a shift, then after the 4LOCK position has been met, display the 4LO lamp solid. In a blocked condition, the 4LO lamp will flash during the 5 Phase 1 attempts. After 5 unsuccessful attempts, continue to flash 4LO, Phase 2 shifting will continue until transfer case is in the AWD or 4LO position. If the final position is AWD, turn off the 4LO lamp, if the final position is 4LO, illuminate the 4LO lamp solid. When shift conditions are not met, flash the 4LOCK and 4LO lamps and the NEUTRAL LED remains solid while push the button is depressed.

SHIFT SEQUENCES (PHASE 1 SHIFTS)

Once all the driver controllable conditions for the requested shift have been met, the FCM begins a shift timer with a maximum duration of 1 second per mode sensor target segment. If the shift timer expires before the FCM recognizes to correct mode sensor position, the shift is considered to have been blocked. The blocked shift will increment the blocked shift counter by one. The FCM strategy for handling blocked shifts will be described later. The process the FCM 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.

1. Allow time for Selector Switch debounce; 250 msec +/-50 msec.
2. Activate/deactivate the 4WD system message icons in the instrument cluster as necessary.
3. Engage the shift motor for a maximum of 1 second +/-100 msec per mode sensor target segment in the destination gear's direction while monitoring the mode sensor.
4. Disengage the shift motor when the correct mode sensor position is recognized.
5. Solidly illuminate the achieved position's instrument panel icon, unless the target is AWD.
6. Transmit a bus message that the transfer case shift is complete.
7. If the desired mode sensor position is not reached after the shift timer expires (i.e.: a blocked shift motor or other condition exists), the FCM will 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 mode sensor target segment. The FCM waits for 2.0 seconds +/-50 msec. and repeats the attempt to shift to the desired position.

The exception to the preceding sequence is when a shift from 4LO to AWD is requested. If AWD is requested from the 4LO position, the transfer case is first driven to the 4LOCK position. If the 4LOCK position is reached, the transfer case is then driven back to the AWD position and the shift is considered complete.

SHIFT OUT OF NEUTRAL

The following steps describe the process for a shift out of NEUTRAL.

1. Extinguish the Neutral LED.
2. Engage the shift motor for a maximum of 1 second +/-100 msec toward the transfer case 4LOCK mode position while monitoring the mode sensor position.
3. Disengage the shift motor when the correct mode sensor position is recognized.
4. Extinguish the Neutral LED.
5. Transmit a bus message that the transfer case shift is complete.
6. If the desired mode sensor position is not received after the shift timer expires (i.e. 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 FCM waits for 2.0 seconds +/-50 msec. and repeats the attempt to shift to the desired position.
7. When the Neutral button is released, if the 4LOCK position is the desired position, the shift is complete. Illuminate the 4LOCK message icon.
8. 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 requirements for shifting are not met, illuminate the 4LOCK message icon and flash the destination message icon as an indication to the driver that all of the driver controllable shift conditions are not being met). If this requires another range or mode shift, begin the range/mode shift process.
9. If the desired mode sensor position is not achieved after the shift timer expires (i.e. a blocked or other condition exists), refer to the section on Blocked Shift Strategy, also known as Phase 2 shifts.

NEUTRAL BLOCKED SHIFT STRATEGY (PHASE 2 SHIFTS)

When a shift is commanded out of neutral, the shift motor will be driven towards its destination position, except in the case of shifting out of NEUTRAL if 4LO was selected (the transfer case will shift to the 4LOCK position first, before proceeding to 4LO). If the shift is blocked on the way to the destination, the FCM 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 position during the shift re-attempts, the message icon for the achieved gear position 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 mode sensor position. If this motor drive allows the transfer case to reach the AWD position, 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 FCM will continue 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 4LOCK), the motor will be driven to stall in the direction of 4LOCK or 4LO, depending on the achieved position. Otherwise, the transfer case will be driven in the direction opposite the last attempt with the desired target being 4LOCK or 4LO.

If the transfer case reaches the AWD position when being driven in the 4LOCK direction, then one final 1.0 second drive toward 4LOCK is attempted. If the transfer case then reaches the 4LOCK position, the shift is considered complete and the 4LOCK message icon is illuminated. If the transfer case is still the AWD position, the shift is considered complete and all message icons are extinguished.

NEUTRAL DRIFT SHIFT STRATEGY (PHASE 3 SHIFTS)

Note. If after the 5th blocked shift and reversal attempt, if the transfer case position is in the NEUTRAL or other undesired region, shift attempts will continue until a non-NEUTRAL or a desired position is reached.

Phase 3 is a series of shifts whose intent is to escape from an undesired position that has been reached outside of a shift. A perceived drift of the transfer case into a non-target region without the FCM driving the shift motor will initiate a phase III shift. Phase 3 will be initiated by any non-target region with the exception of a position greater then encoder_4LO_min or less then encoder_4LOCK_max. Whenever these encoder readings have been seen for defined period of time, Phase III shifting will begin.

The shifts in a given Phase 3 shifting event are always in a single-direction, toward the target region from which the drift occurred. These shifts are performed without regard to shift conditions. The timing of each shift should follow the outline of the Phase 1 forward attempts, allowing the shift timer to reach the target. Between each attempt, there is a calibrated delay. After each attempt the shift counter and the Phase 3 max shifts counter will be updated.

SHIFT REVERSAL TARGETS

If the shift timer expires (1.0 seconds per mode sensor position) and the transfer case has not reached the desired position, all shifts will attempt to return to their original position with the exceptions of

1. If the intended shift is going to the High rail from Low and can't make it, but it can make the AWD position, the motor stops at that position. The FCM will not attempt to cross back over NEUTRAL if it does not have to. This means that there was a block on the first attempt to go to 4LOCK and the transfer case has made it through NEUTRAL to a known good position, then the motor will go back only to the AWD position and execute the remainder of the attempts from there.
2. For shifts out of NEUTRAL, any time a shift is commanded out of NEUTRAL, the system needs to get out. The FCM 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 FCM stores the position in memory as the transfer case's intended position. The FCM continuously monitors the mode sensor and if the mode sensor drifts toward into a NEUTRAL region sensor position for 2.0 seconds, the FCM 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 FCM 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 CONTROL

The FCM will have the ability to vary the speed of the transfer case motor through pulse width modulation (PWM). It is recommended to PWM from 0 to 100% at 100Hz.

The PWM will function as follows

1. Apply an initial duty cycle to shift motor control wires.
2. Control the acceleration of the shift motor by increasing the applied duty cycle at a specified rate.
3. Control the deceleration of the shift motor by updating the applied duty cycle to the shift motor control wires at a specified rate based upon the difference between the desired position and the current position.

SHIFT MOTOR BRAKING

Static shift motor braking is utilized under the following conditions

1. Whenever the transfer case is in the AWD or 4LO position.
2. Whenever an invalid mode sensor 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.

SHIFT ATTEMPT LIMIT

To protect the transfer case system, the FCM will impose a limit on the number of shifts that can occur over a calibrated time period. The system will monitor the number of mode sensor position changes that occur in any 30 second time period. If the number of changes is 25 or greater, the system will go into a default mode. The default mode of operation for shifting is that the number of allowed changes 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

1. The attempt limit will not prevent shifts coming out of NEUTRAL, they will be allowed regardless of the counter/timer.
2. 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. Position changes during this period will not be counted towards the default mode limit.
3. A block, regardless of the direction, whether towards destination or back towards reversal target (shift timer expiring), will count as a value of 2 position changes towards the 30 position changes to go into default mode as defined above. Current attempt limit values are 25 transitions in 30 seconds and default mode values are 3 transitions every 15 seconds for 5 minutes.

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 battery (B+) is restored, this memory loss is detected by the TCM and a Diagnostic Trouble Code (DTC) is set.

Scheme 8

An important function of the TCM is to monitor Clutch Volume Indexes (CVI). CVIs represent the volume of fluid needed to compress a clutch pack.

The TCM monitors gear ratio changes by monitoring 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 Output Speed Sensor provides the TCM with output shaft speed information.

By comparing the two inputs, the TCM can determine 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. (Scheme 8)

Gear ratios can be determined by using the 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 volume 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 volumes and when they are monitored/updated

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

1. Shift lever position
2. Throttle position
3. Engine load
4. Fluid temperature
5. Software level

As driving conditions change, the TCM appropriately adjusts the shift schedule. Refer to the following chart to determine the appropriate operation expected, depending on driving conditions.

TCM QUICK LEARN

The quick learn procedure requires the use of the scan tool.

This program allows the electronic transmission system to recalibrate itself. This will provide the proper transmission operation. The quick learn procedure should be performed if any of the following procedures are performed

1. Transmission Assembly Replacement
2. Transmission Control Module Replacement
3. Solenoid Pack Replacement
4. Clutch Plate and/or Seal Replacement
5. Valve Body Replacement or Recondition

To perform the Quick Learn Procedure, the following conditions must be met

1. The brakes must be applied
2. The engine speed must be above 500 rpm
3. The throttle angle (TPS) must be less than 3 degrees
4. The shift lever position must stay in PARK until prompted to shift to overdrive
5. The shift lever position must stay in overdrive after the Shift to Overdrive prompt until the scan tool indicates the procedure is complete.
6. The calculated oil temperature must be above 60° and below 200°

DRIVE LEARN

When a transmission is repaired and a Quick Learn procedure has been performed on the Transmission 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.

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 transmission is put into gear after the vehicle is allowed to set with the engine not running for at least 10 minutes. Use the following steps to have the TCM learn the 1st N-D UD CVI.

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 performing 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 performed 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 temperatures, but these values (line pressure correction values) are not available for viewing on the scan tool.

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 monitor Norm N-D UD CVI volume until the value stabilizes. 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.

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 stabilizes.

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 stable.

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.
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 KICKDOWN

Use 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 pulldowns 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 transmission 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 the vehicle through 88 km/h (55mph) at a steady 10-15 degree throttle opening and perform multiple 4-5 upshifts.
2. Repeat step 1 until the 4-5 shift become smooth and the Alt 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.