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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 970 (ENGINE CONTROLS - 4.8L, 5.3L, & 6.0L (INTRODUCTION))REPAIR INSTRUCTIONSPOWERTRAIN CONTROL MODULE (PCM) REPLACEMENTINSTALLATION 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 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Install the PCM.

    Ensure that the mounting tabs are engaged.

  2. Secure the spring latch to the PCM.
    3. Fig 1: View Of PCM
    GM814119Courtesy of GENERAL MOTORS CORP.
  3. Connect the PCM electrical connectors.
    NOTE: Refer to Fastener Notice in Cautions and Notices.
  4. Tighten the PCM electrical connector bolts (2).

    Tighten:  Tighten the bolts to 8 N.m (71 lb in).

    5. Fig 2: View Of PCM Electrical Connectors
    GM814117Courtesy of GENERAL MOTORS CORP.
  5. Install the PCM cover.
    6. Fig 3: View Of PCM Cover & Mounting Bracket
    GM814118Courtesy of GENERAL MOTORS CORP.
  6. If equipped with RPO NYS, install the harness ground clip to the PCM cover.
    7. Fig 4: Harness Ground Clip At PCM Cover
    GM865883Courtesy of GENERAL MOTORS CORP.
  7. Connect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) or Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical.
  8. If a NEW PCM was installed, program the PCM. Refer to Service Programming System (SPS) in Programming.
  9. Perform the crankshaft position (CKP) system variation learn procedure. Refer to CKP System Variation Learn Procedure .
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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.