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.
Self-Diagnostic System: Notes
Body Control Module (BCM) is equipped with a self-diagnostic system which detects system abnormalities. When a malfunction occurs, BCM will store a DTC. See BODY CONTROL MODULE (BCM) DTC DEFINITIONS . Malfunctions are recorded as history/intermittent failures or as current failures. Current DTCs indicate BCM has detected a fault which is currently present. A history DTC indicates that BCM has previously detected a malfunction that is not currently present.
The BCM Diagnostic System Check is the starting point for identifying which module(s) on the class 2 device is responsible for issuing the DTC. The Diagnostic System Check will direct the technician to the correct diagnostic procedure for the identified module.
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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.