Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.