Electronic Control Modules - Service Information: Other Dodge Magnum I

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.

Scheme 16

The Antilock Brake Module (ABM) is a microprocessor-based device which monitors the Antilock Brake System (ABS) during normal braking and controls it when the vehicle is in an ABS stop. The ABM also monitors the Electronic Stability Program (ESP) if so equipped. The ABM (3) is mounted to the HCU (2) as part of the Integrated Control Unit (ICU). The ABM uses a 47-way connector on the vehicle wiring harness. The power source for the ABM is through the ignition switch in the RUN or ON position. The ABM is on the CAN-C bus.

The ABM (3) is mounted to the HCU (2) as part of the Integrated Control Unit (ICU). The ABM uses a 47-way connector on the vehicle wiring harness. The power source for the ABM is through the ignition switch in the RUN or ON position. The ABM is on the CAN-C bus.

ANTI-PINCH

The "Anti-Pinch" function is a safety feature that senses obstacles at the top of the glass and anywhere on the seal where it meets the glass to close during the window closing operation. When a front window switch is pressed to the "Auto-Up" position and the closing window traps an object and the sense current passes its limit, the module will stop the motor and drive the window down approximately 200 millimeters. The pinch force is speed dependent which means that if the vehicle is going over 2km per hour the pinch force will be higher than if the vehicle is stopped.

PANIC MODE

If the window switch is held in the "Auto-Up" position and the closing window traps an object, the module will stop the motor and when the switch is released will drive the window in the opposite direction approximately 10 millimeters. If within 8 seconds after the switch was released to the neutral position, the switch is held again to the "Auto-Up" position, the module will enter the second panic mode. During the second panic mode, the module will drive the motor with full (stall) force and stop. If within 8 seconds after the switch is released again to the neutral position, the switch is held again to the "Auto-Up" position, the module will drive the motor again with full (stall) force and stop.

Scheme 17

Note. A battery reconnect procedure must be performed anytime the battery has been disconnected. (Refer to ELECTRICAL/BATTERY SYSTEM - STANDARD PROCEDURE) .

1. Disconnect and isolate the battery negative cable.
2. Remove front door trim panel «(Refer to BODY/DOOR - FRONT/TRIM PANEL - REMOVAL)»(ref-246917-S34781481172007011000000) .
3. Disconnect electrical harness connectors.
4. Remove mounting fasteners and module.

Scheme 18

Note. A battery reconnect procedure must be performed anytime the battery has been disconnected. (Refer to ELECTRICAL/BATTERY SYSTEM - STANDARD PROCEDURE) .

1. Position module.
2. Install and tighten mounting fasteners.
3. Connect electrical harness connectors.
4. Install door trim panel «(Refer to BODY/DOOR - FRONT/TRIM PANEL - INSTALLATION)»(ref-246917-S36762118682007011000000) .
5. Connect battery negative cable.

Scheme 19

The Front Control Module (FCM) is a micro controller based module located in the right front corner of the engine compartment. The front control module mates to the power distribution center to form the Integrated Power Module (IPM). The IPM connects directly to the battery and provides the primary means of circuit protection and power distribution for all vehicle electrical systems. The FCM 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 CAN bus circuit.

MEMORY SEAT MODULE

In order to obtain conclusive testing of the memory system, the Controller Area Network (CAN) data bus, and all of the electronic modules that provide inputs to, or receive outputs from the memory system components must be checked. Any diagnosis of the memory system/module should begin with, the use of a scan tool and the appropriate diagnostic service information.

Refer to the appropriate wiring information in ELECTRICAL for complete circuit schematic or connector pin-out information.

Note. Vehicles equipped with the memory/heated seat option utilize a low voltage cut-off feature. This feature turns off the 12v power to the power seat system anytime vehicle voltage is below 11.7v. Be certain to check the vehicle electrical system for proper voltage anytime the power seat system appears inoperative.

Before any testing of the power seat system is attempted, the battery should be fully-charged.

Scheme 20

1. Disconnect and isolate the battery negative cable.
2. Remove the driver seat cushion/cover (2) «(Refer to BODY/SEATS/SEAT CUSHION COVER - REMOVAL)»(ref-246917-S42329994662007011000000) .
3. Pivot the module upward and disconnect the electrical connectors (1).
4. Unsnap the memory seat module (4) from the side brackets.
5. Pull the module rearward to remove it from the front of the seat frame (3).

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 O2S relays. 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 approximately 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

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.

TRANSMISSION CONTROL MODULE - 42RLE

The Transmission Control Module (TCM) is a sub-module within the Powertrain Control Module (PCM). The Powertrain Control Module (PCM) is located in the right rear of the engine compartment, just in front of the windshield. see scheme 29

Scheme 21

The electronic control system consists of various components providing inputs to the transmission control module (TCM). (Scheme 21) The TCM monitors transmission sensors, shift lever position, and bus messages to determine transmission shift strategy. After shift strategies are determined, the TCM controls the actuation of transmission solenoids, which controls the routing of hydraulic fluid within the transmission, by moving a sequence of four valves to make a shift occur.

The NAG1 electronic transmission has a fully adaptive control system. The system performs its functions based on continuous real-time sensor feedback information. In addition the TCM receives information from the PCM (engine management) and ABS (chassis systems) controllers over the CAN bus. The CAN bus is a high-speed communication bus that allows real time control capability between various controllers. Most messages are sent every 20 milliseconds. This means critical information can be shared between the transmission, engine, and ABS controllers. The CAN bus is a two wire bus with a CAN Bus (+) circuit and a CAN Bus (-) circuit. These circuits are twisted pairs in the harness to reduce the potential of radio and noise interference.

The transmission control system automatically adapts to changes in engine performance, vehicle speed, and transmission temperature variations to provide consistent shift quality. The control system ensures that clutch operation during up-shifting and downshifting is more responsive without increased harshness. The TCM activates the solenoid valves and moves valves in the valve body to achieve the necessary gear changes. The required pressure level is calculated from the load condition, engine speed. Vehicle speed (from ABS module) and transmission oil temperature, matched to the torque to be transmitted. The TCM is located under the left side of the instrument panel.

The Transmission Control Module (TCM) controls all electronic operations of the transmission. The TCM receives information regarding vehicle operation from both direct and indirect inputs, and selects the operational mode of the transmission. Direct inputs are hard wired 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

1. Battery (B+) voltage
2. Ignition "ON" voltage
3. Transmission Control Relay (Switched B+)
4. Throttle Position Sensor
5. Crankshaft Position Sensor
6. Transmission Range Sensor
7. Pressure Switches
8. Transmission Temperature Sensor
9. Input Shaft Speed Sensor
10. Output Shaft Speed Sensor
11. Line Pressure Sensor

Some examples of indirect inputs to the TCM are

1. Engine/Body Identification
2. Manifold Pressure
3. Target Idle
4. Torque Reduction Confirmation
5. Engine Coolant Temperature
6. Ambient/Battery Temperature
7. Scan Tool Communication

Based on the information received from these various 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

1. Transmission Control Relay
2. Solenoids
3. Torque Reduction Request

Some examples of TCM indirect outputs are

1. Transmission Temperature (to PCM)
2. PRNDL Position (to cluster/CCN)

In addition to monitoring inputs and controlling outputs, the TCM has other important responsibilities and functions

1. Storing and maintaining Clutch Volume Indexes (CVI)
2. Storing and selecting appropriate Shift Schedules
3. System self-diagnostics
4. Diagnostic capabilities (with scan tool)

Note. If the TCM has been replaced, the "Quick Learn Procedure" must be performed. (Refer to ELECTRICAL/ELECTRONIC CONTROL MODULES/TRANSMISSION 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 battery (B+) is restored, this memory loss is detected by the TCM and a Diagnostic Trouble Code (DTC) is set.

Scheme 22

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 22)

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 CLUTCH VOLUMES TABLE identifies the appropriate clutch volumes and when they are monitored/updated

CLUTCH VOLUMES TABLE

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.

TRANSMISSION CONTROL MODULE - NAG1

The transmission control module (TCM) determines the current operating conditions of the vehicle and controls the shifting process for shift comfort and driving situations. It receives this operating data from sensors and broadcast messages from other modules.

The TCM uses inputs from several sensors that are directly hardwired to the controller and it uses several indirect inputs that are used to control shifts. This information is used to actuate the proper solenoids in the valve body to achieve the desired gear.

The shift lever assembly (SLA) has sensors that are monitored by the TCM to calculate shift lever position. The reverse light switch, an integral part of the SLA, controls the reverse light relay control circuit. The Brake/Transmission Shift Interlock (BTSI) solenoid and the park lockout solenoid (also part of the SLA) are controlled by the TCM.

The PCM and ABS broadcast messages over the controller area network (CAN) bus for use by the TCM. The TCM uses this information, with other inputs, to determine the transmission operating conditions.

The TCM

1. determines the momentary operating conditions of the vehicle.
2. controls all shift processes.
3. considers shift comfort and the driving situation.

The TCM controls the solenoid valves for modulating shift pressures and gear changes. Relative to the torque being transmitted, the required pressures are calculated from load conditions, engine RPM, vehicle speed, and ATF temperature.

The following functions are contained in the TCM

1. Shift Program
2. Downshift Safety
3. Torque Converter Lock-Up Clutch.
4. Adaptation.

The TCM continuously checks for electrical problems, mechanical problems, and some hydraulic problems. When a problem is sensed, the TCM stores a diagnostic trouble code (DTC). Some of these codes cause the transmission to go into "Limp-In" or "default" mode. Some DTCs cause permanent Limp-In and others cause temporary Limp-In. The NAG1 defaults in the current gear position if a DTC is detected, then after a key cycle the transmission will go into Limp-in, which is mechanical 2nd gear. Some DTCs may allow the transmission to resume normal operation (recover) if the detected problem goes away. A permanent Limp-In DTC will recover when the key is cycled, but if the same DTC is detected for three key cycles the system will not recover and the DTC must be cleared from the TCM with the appropriate scan tool.

Note. If the TCM has been replaced, the "TCM Adaptation Procedure" must be performed. (Refer to ELECTRICAL/ELECTRONIC CONTROL MODULES/TRANSMISSION CONTROL MODULE - STANDARD PROCEDURE)

TCM SIGNALS

The TCM registers one part of the input signals by direct inputs, the other part by CAN bus. In addition to the direct control of the actuators, the TCM sends various output signals by CAN bus to other control modules.

Selector Lever Position

A series of sensors in the SLA inform the TCM of the position of the selector lever.

The TCM monitors the SLA for all shift lever positions through five position circuits. The SLA provides a low-current 12-volt signal to the TCM. The TCM compares the on/off signals to programmed combinations to determine the exact position of the shift lever.

ATF Temperature Sensor

The ATF temperature sensor is a positive temperature co-efficient (PTC) thermistor. It measures the temperature of the transmission fluid and is a direct input signal for the TCM. The temperature of the ATF has an influence on the shifttime and resulting shift quality. As the temperature rises, resistance rises, and therefore, the probing voltage is decreasing. Because of its registration, the shifting process can be optimized in all temperature ranges.

The ATF temperature sensor is wired in series with the park/neutral contact. The temperature signal is transmitted to the TCM only when the reed contact of the park/neutral contact is closed because the TCM only reads ATF temperature while in any forward gear, or REVERSE. When the transmission is in PARK or NEUTRAL, the TCM will substitute the engine temperature for the ATF temperature.

Starter Interlock

The TCM monitors a contact switch wired in series with the transmission temperature sensor to determine PARK and NEUTRAL positions. The contact switch is open in PARK and NEUTRAL. The TCM senses transmission temperature as high (switch supply voltage), confirming switch status as open. The TCM then broadcasts a message over CAN bus to confirm switch status. The PCM receives this information and allows operation of the starter circuit.

N2 and N3 Speed Sensors

The N2 and N3 Input Speed Sensors are two Hall-effect speed sensors that are mounted internally in the transmission and are used by the TCM to calculate the transmission's input speed. Since the input speed cannot be measured directly, two of the drive elements are measured. Two input speed sensors were required because both drive elements are not active in all gears.

CAN Bus Indirect Input Signals

A 2.5-volt bias (operating voltage) is present on the CAN bus any time the ignition switch is in the RUN position. Both the TCM and the ABS apply this bias. On this vehicle, the CAN bus is used for module data exchange only. The indirect inputs used on the NAG1 electronic control system are

1. Wheel Speed Sensors.
2. Transfer Case Switch Status.
3. Brake Switch.
4. Engine RPM.
5. Engine Temperature.
6. Cruise Control Status.
7. Gear Limit Request.
8. Throttle Position - 0% at idle, 100% at WOT. If open, TCM assumes idle (0% throttle opening).
9. Odometer Mileage
10. Maximum Effective Torque.
11. Engine in Limp-In Mode/Mileage Where DTC Was Set.

BRAKE TRANSMISSION SHIFT INTERLOCK (BTSI)

The BTSI solenoid prevents shifting out of the PARK position until the ignition key is in the RUN position and the brake pedal is pressed. The TCM controls the ground while the ignition switch supplies power to the BTSI solenoid. The PCM monitors the brake switch and broadcasts brake switch status messages over the CAN C bus. If the park brake is depressed and there is power (Run/Start) to SLA, the BTSI solenoid deactivates. The TCM monitors this for the SLA because the SLA does not communicate on the CAN bus.

The basic shift schedule includes up and downshifts for all five gears. The TCM adapts the shift program according to driving style, accelerator pedal position and deviation of vehicle speed. Influencing factors are

1. Road Conditions.
2. Incline, Decline and Altitude.
3. Trailer Operation, Loading.
4. Engine Coolant Temperature.
5. Cruise Control Operation.
6. Sporty Driving Style.
7. Low and High ATF Temperature.

DOWNSHIFT SAFETY

Selector lever downshifts are not performed if inadmissible high engine RPM is sensed.

ADAPTATION

To equalize tolerances and wear, an automatic adaptation takes place for

1. Shift Time.
2. Clutch Filling Time.
3. Clutch Filling Pressure.
4. Torque Converter Lock-Up Control.

Adaptation data may be stored permanently and to some extent, can be diagnosed.

Driving Style Adaptation

The shift point is modified in steps based on the information from the inputs. The control module looks at inputs such as

1. vehicle acceleration and deceleration (calculated by the TCM).
2. rate of change as well as the position of the throttle pedal (fuel injection information from the PCM).
3. lateral acceleration (calculated by the TCM).
4. gear change frequency (how often the shift occurs).

Based on how aggressive the driver is, the TCM moves up the shift so that the present gear is held a little longer before the next upshift. If the driving style is still aggressive, the shift point is modified up to ten steps. If the driving returns to normal, then the shift point modification also returns to the base position.

This adaptation has no memory. The adaptation to driving style is nothing more than a shift point modification meant to assist an aggressive driver. The shift points are adjusted for the moment and return to base position as soon as the inputs are controlled in a more normal manner.

Permanent Limp-In Mode

When the TCM determines there is a non-recoverable condition present that does not allow proper transmission operation, it places the transmission in permanent Limp-In Mode. When the condition occurs the TCM turns off all solenoids as well as the solenoid supply output circuit. If this occurs while the vehicle is moving, the transmission remains in the current gear position until the ignition is turned off or the shifter is placed in the "P" position. When the shifter has been placed in "P," the transmission only allows 2nd gear operation. If this occurs while the vehicle is not moving, the transmission only allows operation in 2nd gear.

Temporary Limp-In Mode

This mode is the same as the permanent Limp-In Mode except if the condition is no longer present, the system resumes normal operation.

Under Voltage Limp-In Mode

When the TCM detects that system voltage has dropped below 8.5 volts, it disables voltage-dependant diagnostics and places the transmission in the temporary Limp-In Mode. When the TCM senses that the voltage has risen above 9.0 volts, normal transmission operation is resumed.

Hardware Error Mode

When the TCM detects a major internal error, the transmission is placed in the permanent Limp-In Mode and ceases all communication over the CAN bus. When the TCM has entered this mode normal transmission operation does not resume until all DTCs are cleared from the TCM.

Loss of Drive

If the TCM detects a situation that has resulted or may result in a catastrophic engine or transmission problem, the transmission is placed in the neutral position. Improper Ratio, Input Sensor Overspeed or Engine Overspeed DTCs cause the loss of drive.

Controlled Limp-in Mode

When a failure does not require the TCM to shut down the solenoid supply, but the failure is severe enough that the TCM places the transmission into a predefined gear, there are several shift performance concerns. For instance, if the transmission is slipping, the controller tries to place the transmission into 3rd gear and maintain 3rd gear for all forward drive conditions.

TCM QUICK LEARN - 42RLE Only

The quick learn procedure requires the use of the appropriate 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°

TCM ADAPTATION - NAG1 Only

The adaptation procedure requires the use of the appropriate scan tool. This program allows the electronic transmission system to re-calibrate itself. This will provide the proper baseline transmission operation. The adaptation procedure should be performed if any of the following procedures are performed

1. Transmission Assembly Replacement
2. Transmission Control Module Replacement
3. Clutch Plate and/or Seal Replacement
4. Electrohydraulic Unit Replacement or Recondition

1. With the scan tool, reset the Transmission adaptives. Resetting the adaptives will set the adaptives to factory settings. NOTE: Perform the Coast Down Adaptations first. The Transmission Temperature must be greater than 60°C (140°F) and less than 70°C (158°F). Failure to stay within these temperature ranges will void the procedure.
2. Drive the vehicle until the transmission temperature is in the specified range.
3. Perform 4 to 5 coast downs from 5th to 4th gear and then 4th to 3rd gear. NOTE: For Upshift adaptation, the Transmission temperature must be greater than 60°C (140°F) and less than 100°C (212°F). Failure to stay within these temperature ranges will void this procedure.
4. From a stop, moderately accelerate the vehicle and obtain all forward gear ranges while keeping the Engine RPM below 1800 RPM. Repeat this procedure 4 to 5 times.
5. Obtaining 5th gear may be difficult at 1800 RPM. Allow the transmission to shift into 5th gear at a higher RPM then lower the RPM to 1800 and perform manual shifts between 4th and 5th gears using the shift lever.
6. The TCM will store the adaptives every 10 minutes. After completion of the adaptation procedure make sure the vehicle stays running for at least 10 minutes.
7. It is possible to manually store the adaptives under the 10 minute time frame using the scan tool Store Adaptives procedure.