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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1601 (BODY CONTROL SYSTEM)REPAIR INSTRUCTIONSBODY WIRING HARNESS EXTENSION REPLACEMENT - BCMINSTALLATION PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Installation Procedure

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Installation 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: Ensure the sliding latch is fully extended before connecting the body wiring extension to the rear electrical center.
  1. Using a downward motion, install the body wiring extension (1) to the rear electrical center.
    Fig 1: Removing/Installing Body Wiring Extension In Rear Electrical Center
    GM836844Courtesy of GENERAL MOTORS CORP.
    2. Fig 2: Disconnecting/Connecting BCM Connectors
    GM709161Courtesy of GENERAL MOTORS CORP.
  2. Connect the 24-way gray electrical connector (1) to the BCM.
  3. Connect the 32-way tan electrical connector (2) to the BCM.
  4. Connect the body wiring extension (1) to the BCM.
    Fig 3: Wiring Extension & BCM
    GM684396Courtesy of GENERAL MOTORS CORP.
  5. Engage the sliding latch fastening the BCM to the rear electrical center.
    Fig 4: Identifying Rear Electrical Center Locking Tab
    GM728745Courtesy of GENERAL MOTORS CORP.

    Slide the latch outboard until the locking tab (1) is fully seated.

  6. Install the rear electrical center cover.
    Fig 5: View Of Rear Electrical Center Cover
    GM683548Courtesy of GENERAL MOTORS CORP.
  7. If replacing the body wiring harness extension on a Chevrolet TrailBlazer, GMC Envoy or Oldsmobile Bravada, position the left hand second seat to a passenger position.
  8. If replacing the body wiring harness extension on a Chevrolet TrailBlazer EXT or GMC Envoy XL, install the left second row seat. Refer to SEAT BACK REPLACEMENT - REAR NO. 1 (TRAILBLAZER EXT, ENVOY XL) in Seats.
  9. Connect the negative battery cable. Refer to BATTERY NEGATIVE CABLE DISCONNECT/CONNECT PROCEDURE in Engine Electrical.
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.