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.
Powertrain Control Module
The PCM communicates with the BCM over the Class 2 serial data circuit. When the BCM enters tamper mode, it sends a Class 2 message to the PCM in order to disable the fuel injection system. If the BCM receives the expected ignition code, the BCM sends a class 2 message to the PCM in order to enable the fuel injection system. The PCM then allows the vehicle to start.
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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.