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.
Section 16 (Body Control Modules): Operation: Notes
The Body Control Module (BCM) has 2 main power feeds (high and low current) and 2 main grounds. Low power feed (battery 1) is used to supply power for BCM's logic and internal driver operation. Operating current at low power feed should not exceed 3 amps. High power feed is used to supply power for systems that draw higher amounts of current. Operating current at high power feed should not exceed 7.5 amps for 2 seconds when BCM is awake or 2.5 milliamps when BCM is asleep. For most functions, BCM system voltage should be 9-16 volts. If voltage exceeds 16 volts, BCM will disable functions that could be damaged.
If a BCM malfunction would result in unacceptable vehicle operation, BCM will take fail-soft action to minimize the condition (i.e., BCM will substitute a fixed input or output value if BCM is unable to interpret data).
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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.