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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 975 (ENGINE CONTROLS - 4.3L (INTRODUCTION))REPAIR INSTRUCTIONSIDLE AIR CONTROL (IAC) VALVE 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 and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. If installing a NEW IAC valve, measure the distance between the IAC valve pintle and the mounting flange. If the distance is more than 28 mm (1.10 in), use finger pressure, and gently push in the pintle.
    2. Fig 1: Measuring Distance Between IAC Valve Pintle & Mounting Flange
    GM17065Courtesy of GENERAL MOTORS CORP.
  2. Install a NEW IAC valve O-ring seal.
  3. Lubricate the IAC valve O-ring seal with clean engine oil.
  4. Install the IAC valve and O-ring seal.
    5. Fig 2: View Of IAC Valve & O-Ring Seal
    GM12910Courtesy of GENERAL MOTORS CORP.
  5. If installing the old IAC valve, clean the old thread locking material from the screws.
  6. If installing the old IAC valve coat the screw threads with threadlock GM P/N 12345382 (Canadian P/N 10953489), or equivalent.
    NOTE: Refer to Fastener Notice in Cautions and Notices.
  7. Install the IAC valve screws.

    Tighten:  Tighten the screws to 3 N.m (27 lb in).

    8. Fig 3: View Of IAC Valve Screws
    GM12909Courtesy of GENERAL MOTORS CORP.
  8. Connect the IAC valve electrical connector (2).
    9. Fig 4: View Of TP Sensor, IAC Motor, ECT Sensor, Control Port Injector Module & Engine Harness Clip Bolt
    GM782174Courtesy of GENERAL MOTORS CORP.
  9. Install the air cleaner outlet resonator. Refer to Air Cleaner Outlet Resonator Replacement .
  10. Perform the IAC reset procedure:
    1. Turn the ignition to the ON position, wait for 5 seconds.
    2. Turn the ignition to the OFF position, wait for 10 seconds.
    3. Start the engine and check for proper idle speed.
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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.