Powertrain Control Module

NOTE: If battery is disconnected or voltage supply to PCM is lost, PCM must relearn shift characteristics. It may be necessary to perform shift quality quick-learn procedure so PCM can relearn shift characteristics. See SHIFT QUALITY QUICK-LEARN PROCEDURE under PROGRAMMING.

CAUTION: If PCM is replaced, speedometer signal MUST be calibrated for current application by performing pinion factor procedure. See PINION FACTOR PROCEDURE under PROGRAMMING. Failure to perform this procedure will result in faulty or no speedometer operation. PCM may also require flash update. Contact local dealer for updates through Mopar Diagnostic System (MDS).

PCM may receive signal data in 2 ways: directly from a sensor or component, or through a twisted-pair bus circuit which connects all of the vehicle computer systems. This modulated bidirectional bus system is referred to as Chrysler Collision Detection (CCD) bus. Bus system allows the various vehicle control modules to share signal data. If a bus failure is present, default values are substituted by PCM, allowing continued, but limited operation.

Direct battery voltage is supplied to PCM. If PCM looses battery voltage, transaxle will enter limp-in mode. For additional information on limp-in mode, see LIMP-IN MODE . When PCM receives an ignition run signal from ignition switch, it performs a series of circuit and relay checks. If no problem is found, PCM provides voltage to transmission control relay, causing contacts to close which supplies voltage to solenoid assembly.

PCM contains a self-diagnostic system which stores a DTC if a transaxle failure is present. DTCs can be retrieved to identify transaxle problem areas. If malfunction goes away after DTC is stored in PCM memory, PCM will erase DTC after ignition has been cycled at least 40 times.

PCM contains an adaptive control program which learns application and release rates of transaxle components for smooth operation. PCM also learns the rate at which applied elements build pressure sufficient for a speed change.