Transaxle Control Module (TCM)

The TCM 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 bi-directional bus system is called Chrysler Collision Detection (CCD) bus and allows the various vehicle control modules to share signal data. If CCD bus failure exists, default values are substituted by the TCM, allowing continued, but limited operation.

Direct battery voltage is supplied to TCM. If TCM loses battery voltage, transaxle will enter limp-in mode. For additional information on limp-in mode, see LIMP-IN MODE under OPERATION. 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 transaxle control relay, causing contacts to close, supplying voltage to solenoid assembly.

NOTE: Transaxle control relay may also be referred to as "transmission control relay" or "trans. system relay".

The TCM contains a self-diagnostic system, which stores a Diagnostic Trouble Code (DTC) if transaxle failure exists. DTC's can be retrieved to identify transaxle problem areas. If malfunction goes away after diagnostic trouble code is stored in TCM memory, the TCM will erase diagnostic trouble code after ignition has been cycled at least 75 times.

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