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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1410 (ENGINE CONTROL SYSTEM - 4.2L (INTRODUCTION))DESCRIPTION AND OPERATIONELECTRONIC IGNITION (EI) SYSTEM DESCRIPTIONPOWERTRAIN CONTROL MODULE (PCM)
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Powertrain Control Module (PCM)

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Powertrain Control Module (PCM)
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.

The PCM controls all ignition system functions, and constantly corrects the spark timing. The PCM monitors information from various sensor inputs that include the following:

  • The throttle position (TP) sensor
  • The engine coolant temperature (ECT) sensor
  • The mass air flow (MAF) sensor
  • The intake air temperature (IAT) sensor
  • The vehicle speed sensor (VSS)
  • The transmission gear position or range information sensors
  • The engine knock sensors (KS)
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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  • • 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.