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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1410 (ENGINE CONTROL SYSTEM - 4.2L (INTRODUCTION))REPAIR INSTRUCTIONSPOWERTRAIN CONTROL MODULE (PCM) REPLACEMENTREMOVAL PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Removal Procedure

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Removal Procedure
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
    IMPORTANT: It is necessary to record the remaining engine oil life. If the replacement module is not programed with the remaining engine oil life, the engine oil life will default to 100%. If the replacement module is not programmed with the remaining engine oil life, the engine oil will need to be changed at 5000 km (3,000 mi) from the last engine oil change.
  1. Using a scan tool, retrieve the percentage of remaining engine oil. Record the remaining engine oil life.
    2. Fig 1: View Of PCM Assembly
    GM1284769Courtesy of GENERAL MOTORS CORP.
  2. Loosen the PCM harness connector bolts (4) from the center of the PCM harness connectors.
    3. NOTE: In order to prevent internal damage to the PCM, the ignition must be OFF when disconnecting or reconnecting the PCM connector.
  3. Remove the PCM harness connectors (2) from the PCM (1).
  4. Remove the PCM retaining bolts (3) and nuts (6).
    5. NOTE: Refer to PCM and ESD Notice in Cautions and Notices.
  5. Slide the PCM (1) away from the intake manifold past the mounting studs (5) and remove PCM from the vehicle.
  6. Remove the PCM mounting studs (5) from the intake manifold ONLY if replacing the studs.
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.