Electronic Control Modules: Other Dodge Pickup R2500

ECM INPUTS

1. Accelerator Pedal Position Sensor (APPS) Volts.
2. APPS1 Signal - For off engine APPS.
3. APPS2 Signal - For off engine APPS.
4. APPS Idle Validation Switches #1 and #2.
5. Battery voltage.
6. Camshaft Position Sensor (CMP).
7. CCD bus (+) circuits.
8. CCD bus (-) circuits.
9. Crankshaft Position Sensor (CKP).
10. Data link connection for DRBIII(R) scan tool.
11. Engine Coolant Temperature (ECT) sensor.
12. Ground circuits.
13. Fuel Pressure Sensor.
14. Battery Temperature.
15. Fan speed
16. Inlet Air Temperature Sensor/Pressure Sensor.
17. Intake Air Temperature Sensor/MAP Sensor.
18. Oil Pressure Switch.
19. Power ground.
20. Sensor return.
21. Signal ground.
22. Water-In-Fuel (WIF) sensor.

ECM OUTPUTS

After inputs are received by the ECM, certain sensors, switches and components are controlled or regulated by the ECM. These are considered ECM Outputs. These outputs are for

1. CCD bus (+) circuits.
2. CCD bus (-) circuits.
3. CKP and APPS outputs to the PCM.
4. Data link connection for DRBIII(R) scan tool.
5. Five-volt sensor supply.
6. Fuel transfer (lift) pump.
7. Intake manifold air heater relays #1 and #2 control circuits.
8. Malfunction indicator lamp (Check engine lamp) (databus).
9. Oil Pressure Switch/warning lamp (databus).
10. Fuel Control Actuator.
11. Wait-to-start warning lamp (databus).
12. Fan Clutch PWM.
13. Water-In-Fuel (WIF) warning lamp (databus).

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 or O2S heater 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. 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 - A/T 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 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-pressure A/C switches. Refer to «HEATING & AIR CONDITIONING»(ref-189721) for additional information.
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 - A/T 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 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-pressure A/C switches. Refer to «HEATING & AIR CONDITIONING»(ref-189721) for additional information.

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 - A/T 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(s) 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 - A/T only).
11. 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 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(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.

PCM INPUTS

1. ABS module (if equipped).
2. A/C request (if equipped with factory A/C).
3. A/C select (if equipped with factory A/C).
4. A/C pressure transducer.
5. Auto Shutdown (ASD) sense.
6. Battery temperature sensor.
7. Battery voltage.
8. Brake switch.
9. J1850 bus (+) circuits.
10. J1850 bus (-) circuits.
11. Camshaft position sensor signal.
12. Crankshaft position sensor.
13. Data link connection for DRBIII(R) scan tool.
14. EATX module (if equipped).
15. Engine coolant temperature sensor.
16. Fuel level (through J1850 circuitry).
17. Generator (battery voltage) output.
18. Ignition circuit sense (ignition switch in on/off/crank/run position).
19. Intake manifold air temperature sensor.
20. Knock sensors (2 on 3.7L engine).
21. Leak detection pump (switch) sense (if equipped).
22. Manifold Absolute Pressure (MAP) sensor.
23. Oil pressure.
24. Oxygen sensors.
25. Park/neutral switch (A/T only).
26. Power ground.
27. Power steering pressure switch (if equipped).
28. Sensor return.
29. Signal ground.
30. Speed control multiplexed single wire input.
31. Throttle position sensor.
32. Transfer case switch (4WD range position).
33. Vehicle speed signal.

PCM OUTPUTS

1. A/C clutch relay.
2. Auto shutdown (ASD) relay.
3. J1850 bus (+/-) circuits for: speedometer, voltmeter, fuel gauge, oil pressure gauge/lamp, engine temp, gauge and speed control warning lamp.
4. Data link connection for DRBIII(R) scan tool.
5. EGR valve control solenoid (if equipped).
6. EVAP canister purge solenoid.
7. Five volt sensor supply (primary).
8. Five volt sensor supply (secondary).
9. Fuel injectors.
10. Fuel pump relay.
11. Generator field driver (-).
12. Generator field driver (+).
13. Idle Air Control (IAC) motor.
14. Ignition coil(s).
15. Leak detection pump (if equipped).
16. Malfunction indicator lamp (Check engine lamp). Driven through J1850 circuits.
17. Oxygen sensor heater relays.
18. Oxygen sensors (pulse width modulated).
19. Radiator cooling fan relay (pulse width modulated).
20. Speed control vacuum solenoid.
21. Speed control vent solenoid.
22. Tachometer (if equipped). Driven through J1850 circuits.
23. Transmission converter clutch circuit. Driven through J1850 circuits.

STANDARD PROCEDURE - PCM/SKIM PROGRAMMING

Note. There are two procedures for transferring the secret key to the SKIM: When ONLY the SKIM module is replaced, the secret key is transferred from the PCM to the SKIM. The ORIGINAL KEYS may then be programmed to the SKIM. When ONLY the PCM is replaced, then the secret key is transferred from the SKIM to the PCM. The ORIGINAL 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 programmed.

Note. Before replacing the Powertrain Control Module (PCM) for a failed driver, control circuit, or ground circuit, be sure 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., 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 Immobilizer 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 DRBIII(R) scan tool. Perform the following steps to program the secret key into the PCM.

1. Turn the ignition switch on (transmission in park/neutral).
2. Use the DRBIII(R) 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. 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, monitor 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 DRBIII(R) scan tool will ask, "Is odometer reading between XX and XX?" Select the YES or NO button on the DRBIII(R) scan tool. If NO is selected, the DRBIII(R) 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 DRBIII(R) 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 DRBIII(R) scan tool and select THEFT ALARM, SKIM, then MISCELLANEOUS.
3. Select PROGRAM IGNITION KEYS.
4. Enter secured access mode by entering the vehicle four-digit PIN. 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 DRBIII(R) scan tool will display one of the following messages: Programming Not Attempted - The DRBIII(R) scan tool attempts to read the programmed key status and there are no keys programmed into SKIM memory. 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. 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 DRBIII(R) 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.

SHIFT REQUIREMENTS

If the TCCM 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 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.

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

1. Front and rear wheel speed are within 21 KM/H (13 MPH).
2. A change in the Selector switch state indicates that a mode shift has been requested.
3. A valid mode sensor signal is being sensed by the TCCM.
4. Proper transmit/receive messages are occurring on the PCI bus.
5. Ignition key switch is in the RUN position.

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

1. Front and rear wheel speed are within 21 KM/H (13 MPH).
2. A change in the Selector Switch state indicating a range shift has been requested.
3. Transmission in NEUTRAL signal must be recognized for at least 1.5 seconds +/-100 msec. (Automatic transmissions only).
4. Proper transmit/receive messages are occurring on the PCI bus.
5. Clutch signal is recognized for 500 msec +/- 50 msec (Manual transmissions only).
6. Vehicle speed is less than or equal to 4.8 KM/H (3 MPH).
7. Ignition key switch is in the RUN position.
8. A valid mode sensor signal is being sensed by the TCCM.

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

1. Front and rear wheel speed are within 21 KM/H (13 MPH).
2. The recessed Neutral Selection switch has been depressed continuously for 4.0 seconds +/-100 msec while all shift conditions have been continuously met.
3. Transmission in NEUTRAL signal recognized from the bus (Automatic transmissions only)
4. Clutch signal is recognized from the bus (Manual transmissions only).
5. Proper message transmissions/receptions are occurring on the PCI bus.
6. Vehicle speed is less than or equal to 4.8 KM/H (3 MPH).
7. Ignition key switch is in the RUN position, engine off.
8. Foot brake is applied.
9. A valid mode sensor signal is being sensed by the TCCM.

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

1. Front and rear wheel speed are within 21 KM/H (13 MPH).
2. The recessed Neutral Selection switch has been depressed continuously for 1.0 seconds +/-100 msec while all shift conditions have been continuously met.
3. Transmission in NEUTRAL signal recognized from the bus (Automatic transmissions only)
4. Clutch signal is recognized from the bus (Manual transmissions only).
5. Proper message transmissions/receptions are occurring on the PCI bus.
6. Vehicle speed is less than or equal to 4.8 KM/H (3 MPH).
7. Ignition key switch is in the RUN position.
8. Foot brake is applied.
9. A valid mode sensor signal is being sensed by 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.

1. Allow time for Selector Switch debounce; 250 msec +/-50 msec.
2. Extinguish the source gear's LED while flashing desired transfer case position's LED.
3. Engage the shift motor for a maximum of 1 second +/-100 msec per 'D' channel transition in the destination gear's direction while monitoring the mode sensor channel transitions.
4. Disengage the shift motor when the correct mode sensor code is recognized.
5. Solidly illuminate the selected gear's LED.
6. Transmit a bus message that the transfer case shift is complete.
7. If the desired mode sensor code 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. per 'D' channel. The TCCM 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 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 position 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 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

1. Extinguish the Neutral LED.
2. Engage the shift motor for a maximum of 1 second +/-100 msec toward the transfer case 4H mode position while monitoring the mode sensor channel transitions.
3. Disengage the shift motor when the correct mode sensor code 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 code 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 TCCM 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 4H position is the desired position, the shift is complete. Illuminate the 4H LED.
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 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). If this requires another range or mode shift, begin the range/mode shift process.
9. If the desired mode sensor code is not received after the shift timer expires (i.e., a blocked or other condition exists), refer to «BLOCKED SHIFT STRATEGY»(ref-189660-S05905185742005091200000) .

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 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 '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 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 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 positions and the shift conditions are no longer being met, the transfer case will be driven toward the corresponding '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 positions, 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 NEUTRAL 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

1. 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 NEUTRAL 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.
2. 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 into a NEUTRAL region sensor position for 2.0 seconds, 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

1. Whenever the transfer case is in the 2WD/AWD or 4L 'D' channel 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 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 transitions 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. D-channel transitions 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 transitions 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.

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.

CLUTCH VOLUME INDEXES (CVI)

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 see scheme 10

Scheme 7

Gear ratios can be determined by using the DRBIII(R) 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. Refer to CLUTCH VOLUMES table.

CLUTCH VOLUMES

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 see scheme 11

Scheme 8

STANDARD PROCEDURE - TCM QUICK LEARN

The quick learn procedure requires the use of the DRBIII(R) 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 DRBIII(R) indicates the procedure is complete.
6. 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 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 sit 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 DRBIII(R).

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, 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 CVIs.

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 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 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 (55 MPH) 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.