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 Powertrain Control Module (PCM) communicates with the Body Control Module (BCM) over the Class 2 serial data line. When the BCM enters tamper mode, it sends a Class 2 message to the PCM in order to disable the starting and fuel delivery systems. If the BCM receives a valid coded key, the BCM sends a class 2 message to the PCM in order to enable the starting and fuel delivery systems. 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.