Transmission Control Module

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

CAUTION: If TCM 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. TCM may also require flash update. Contact local dealer for updates through Mopar Diagnostic System (MSD).

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

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

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

TCM contains an adaptive control method which learns application and release rates of transaxle components for smooth operation. Adaptive controls allow system to adapt to changes in engine performance and friction element wear that occur over the life of transaxle. TCM also learns the rate at which applied elements build pressure sufficient for a speed change.

TCM uses Clutch Volume Indexes (CVI) to determine the volume of fluid needed to compress a clutch pack. The CVI is continuously updated for adaptive controls. As friction material wears, fluid volume needed to apply clutch pack increases. If TCM, transaxle internal components, solenoid assembly or torque converter are replaced, TCM must relearn shift characteristics. See SHIFT QUALITY QUICK-LEARN PROCEDURE under PROGRAMMING.