Theory Of Operation

The purpose of the diagnostic is to monitor the question-answer Controller Area Network (CAN) communication between the shifter and Transmission Control Module (TCM) by comparing the shifter response to the expected value in the TCM software. The TCM sends two randomly generated values to the shifter and the shifter is expected to answer with a value calculated based upon these two random numbers. The TCM commands the shifter to reset if one of the following conditions occurs:

• No answer received within a calibrated amount of time.
• Received answer is incorrect and is the same as the previous answer.
• Received answer is incorrect and is not the same as the previous answer.