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.
Body Control Module Asleep/Wake-Up Signals
Signals that activate the BCM are known as wake-up signals. BCM is asleep when it is not controlling or monitoring the following wake-up functions:
- Any activity on serial data line.
- Hatch or door ajar switch.
- Hatch release switch.
- Key-in-ignition switch.
- Monitored load relay.
- Any exterior lighting function.
- Battery disconnection and reconnection.
- Ignition is turned on.
The BCM will enter asleep state when there is no activity on serial data line, ignition is turned off, no outputs are commanded, no delay timers are actively counting and no wake-up inputs are present.
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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.