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.
Functional Description - Powertrain Control Module (Pcm)
The Powertrain Control Module (PCM) is the main module controlling operation of the starting system relays. When the PCM receives a CRANK command message it sends a signal to the Body Control Module (BCM) to energize the BCM controlled relay while simultaneously energizing the PCM controlled relay through in internal High Side Driver (HSD). The PCM also disables the double start over ride once the engine is started.
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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.