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 MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1601 (BODY CONTROL SYSTEM)REPAIR INSTRUCTIONSBODY CONTROL MODULE REPLACEMENTREMOVAL PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Removal Procedure
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Removal Procedure
WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
- The ignition switch should be in the OFF position when connecting or disconnecting the connectors to the body control module (BCM).
- Always disconnect the 40-way body wiring extension FIRST, the 32-way tan connector SECOND and the 24-way gray electrical connector LAST.
- Always connect the 24-way gray electrical connector FIRST, the 32-way tan connector SECOND and the 40-way body wiring extension LAST.
- The BCM can set DTCs with the ignition switch in the OFF position. The BCM has battery run down protection for the courtesy lamp circuit. The BCM battery run down protection cannot detect shorts on inputs or other circuits which the BCM does not control. Use the scan tool in order to activate the POWER DOWN NOW mode. Use the POWER DOWN NOW mode in order to check for current draws on circuits that are not controlled by the BCM, or controlled by the battery run down protection system.
- Do not touch the exposed electrical contacts of the body wiring extension. Do not open the BCM housing. The module does not have any serviceable components. The module may be replaced only as an assembly.
RENDER: 1.0x
NO RELATED
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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.