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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 974 (ENGINE CONTROLS - 6.6L (LLY) (INTRODUCTION))REPAIR INSTRUCTIONSTURBOCHARGER LEARN PROCEDURECIRCUIT DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Circuit Description

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Circuit Description
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.

The turbocharger learn procedure is performed automatically during each ignition cycle by the engine control module (ECM). Certain enable criteria must be met for the ECM to perform this procedure. After each ignition cycle, and before the enable criteria for the learn procedure have been met, the ECM will use the previously learned value. If the ECM does not have a previously learn value it will default to a stored calibrated value. The ECM will use this value until the enable criteria have been met, and then it will perform the procedure to learn the new value. If the ECM attempt to perform the procedure and fails, diagnostic trouble codes (DTCs) P0046 or P2563 may set.

The turbocharger learn procedure is required when the following service procedures have been performed:

  • The turbocharger vane position control solenoid valve replacement
  • The turbocharger vane position sensor replacement
  • The engine control module (ECM) replacement
  • The turbocharger replacement
  • Any service that disturbs the turbocharger components
IMPORTANT: Once the enable conditions have been met the throttle must remain at idle. Do not change the accelerator pedal position (APP) during this procedure.
  1. The following conditions must be met for the ECM to perform the turbocharger learn procedure.
    • The A/C is OFF.
    • The vehicle is in Park or Neutral.
    • Start and idle the engine.
    • The engine coolant temperature (ECT) is more than 72°C (162°F).
  2. After the enable conditions have been met for at least 60 seconds, turn OFF the ignition for at least 30 seconds. The system should have learned the new turbocharger position.
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.