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.
Circuit Description
The body control module (BCM) is the power mode master responsible for sending the power mode message on the data buses. The BCM monitors Ignition 1 (Run/Crank) and Ignition 2 (Acc/Run) signals from the ignition switch, and the engine run flag (ERF) in order to determine the present power mode. Refer to Body Control System Description and Operation for the applicable power mode look up table.
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Use the Manual With the Right Hardware
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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.