2003 Chevrolet TrailBlazer 4.2 S, 4WDFACTORY OEM SERVICE PROCEDURE

Engine Control Module Or Powertrain Control Module: Notes

NOTE: DO NOT program an existing PCM with the identical software/calibration package. This procedure is not a short cut to correct a driveability condition. This is an ineffective repair. A PCM should only be programmed when a service procedure instructs you to replace the PCM. The service part PCM does not contain operating software or calibrations or General Motors Corporation releases an updated software/calibration package.

After replacing Powertrain Control Module (PCM) or if program needs to be updated, refer to latest Techline® information on PCM reprogramming. PCM can only be programmed using Tech 2 and Techline® terminal, or by using a personal computer equipped with the current service programming system software installed.

Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

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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.

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