How to Clear a GMC ECM

by Ryan Bauer

The engine control module on GMC vehicles stores a variety of error codes and engine management settings. When this stored content causes problems, a reset of the ECM is in order. Momentarily cutting the system off from its power source is all that's required to force a reset. All codes will be erased, and the ECM will start from a clean slate.

Step 1

Loosen the bolt on the black battery cable until the connector opens enough to come off the battery stud. Place a piece of cardboard between the cable and the stud to ensure no electrical connection remains.

Step 2

Turn the headlights on for several seconds to use up any stored power, then return them to the "off" position.

Step 3

Remove the cardboard and reconnect the battery cable by reversing the previous steps. The ECM has been reset to a clean state.

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