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.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 845 (THEFT DETERRENT SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B3031: SECURITY SYSTEM CONTROLLER IN LEARN MODEDIAGNOSTIC AIDS
1999 GMC Forward Control 5.7 R, Automatic
Diagnostic Aids
1999 GMC Forward Control 5.7 R, AutomaticSECTION Diagnostic Aids
WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
- Prior to replacing a BCM, ensure that all of the diagnostics have been completed. Refer to Diagnostic Trouble Code (DTC) List .
- Inspect the Passlock™ sensor harness for intermittent or poor connections. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
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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.