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.
Start-Up Diagnostics
When the DTCM is activated, the internal circuitry will undergo a diagnostic procedure. The controller will examine all inputs and outputs for short circuits to ground, short circuits to battery and open circuits and will also verify proper module operation and memory operation. If a fault is detected, a message will be sent out over the CAN C bus to the Body Control Module (BCM). The BCM will signal the Instrument Panel Cluster (IPC) to illuminate the lamp indicating that service is recommended.
After passing all diagnostic tests, the controller will receive and process inputs and produce the appropriate outputs. Proper monitoring of the controller inputs and outputs performance will continue.
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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.