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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTCOMMUNICATION DEVICESBODY CONTROL SYSTEMREPAIR INSTRUCTIONSBODY CONTROL MODULE REPLACEMENTINSTALLATION PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Installation Procedure

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Installation Procedure
  1. Index the slots on the BCM (1) to the rear electrical center.
  2. Using a downward motion, install the BCM to the rear electrical center.
    Fig 1: Installing BCM To Rear Electrical Center
    G01640791Courtesy of GENERAL MOTORS CORP.
  3. Connect the 24-way gray electrical connector (1) to the BCM.
  4. Connect the 32-way tan electrical connector (2) to the BCM.
    Fig 2: Connecting 32-Way Tan Electrical Connector To BCM
    G01640792Courtesy of GENERAL MOTORS CORP.
  5. Connect the 40-way body wiring extension (1) to the BCM.
    Fig 3: Connecting 40-Way Body Wiring Extension To The BCM
    G01640793Courtesy of GENERAL MOTORS CORP.
  6. Engage the sliding latch fastening the BCM to the rear electrical center.

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

    Fig 4: Sliding Latch Outboard Until Locking Tab Is Fully Seated
    G01640794Courtesy of GENERAL MOTORS CORP.
  7. Install the rear electrical center cover.
  8. If replacing the BCM on a Chevrolet TrailBlazer, GMC Envoy or Oldsmobile Bravada, position the left hand second seat to a passenger position.
  9. If replacing the BCM on a Chevrolet TrailBlazer EXT or GMC Envoy XL, install the left second row seat. Refer to SEAT SYSTEM  in Seats.
  10. Connect the negative battery cable. Refer to BATTERY NEGATIVE CABLE DISCONNECT/CONNECT PROCEDURE  in Engine Electrical.
  11. If installing a replacement BCM, program the BCM. Refer to BODY CONTROL MODULE (BCM) PROGRAMMING/RPO CONFIGURATION   . 
    Fig 5: Installing Rear Electrical Center Cover
    G01640795Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

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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.