On-Board Diagnostics

The transmission control module monitors operation of the transmission control system. Some components are monitored continuously, others only during specified operating conditions. When the transmission control module detects a malfunction lasting longer than a specified period of time the transmission control module will generate an error code that can be detected at the diagnostic connector.

There are 32 diagnostic items plus 6 fail safe items that will generate diagnostic codes. The malfunction codes are erased when the vehicle battery is disconnected for more than ten seconds.

If multiple malfunctions occur the diagnostic codes will be sent sequentially beginning with the lowest number code in ascending order with a 2 second pause between each code. A maximum of up to 10 fault codes can be stored in the control module's memory. If the number of stored codes exceeds 10, previously stored codes will be erased, beginning with the oldest code.

If the fail-safe system is activated, the transaxle will be locked in one forward gear while in any of the forward gear positions. This is provided so that the customer can "limp" the vehicle to a repair facility without causing further damage to the transmission.

The Transmission Control Module (TCM) continuously monitors critical transaxle input and output circuits within the system, verifying correct operation. Each circuit monitored by the TCM has a corresponding fault message assigned to it. If the on-board diagnostic system senses that one of the circuits is malfunctioning, it stores the corresponding fault message in memory. This information can aid in transaxle diagnosis. In the event of a component failure, the Transmission Control Module will compensate by adjusting the transmission shift pattern. The appropriate Diagnostic Trouble Code will also be set into the TCM's memory.