How to Reset a Computer in a 2002 GMC Envoy

by Jamie Ratliff

The 2002 GMC Envoy has an electronically controlled engine that requires a computer to function properly. The computer, a Power train Control Module or PCM, monitors the engine's sensors and makes adjustments, as necessary, to enhance engine performance. If the PCM is not operating correctly, the engine may run rough and gas mileage may be lower than normal. The PCM may need to be reset when an engine sensor or electronic part is replaced. The procedure to reset the PCM is easy, even for the novice mechanic.

Step 1

Park and turn off the vehicle's ignition. Open and secure the hood. Disconnect the negative battery cable with an adjustable wrench.

Step 2

Turn on the vehicle's headlight switch inside the vehicle's passenger compartment. The lights will not come on with the battery disconnected, but any remaining power will drain. Wait five minutes and turn off the headlight switch.

Step 3

Connect the negative battery cable with an adjustable wrench.

Step 4

Drive the vehicle for at least 30 minutes to allow the computer time to reset.

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