GM Service Manual Online
For 1990-2009 cars only

Clearing BCM DTCs

Current DTCs (21 to 24) are displayed as long as the BCM detects the fault to be current in the diagnostic mode. History DTCs (31 to 34) remain stored by the body control module (BCM) until cleared. Current and history DTCs can be cleared by depressing and holding the door lock switch in the unlock position for 4 seconds while the BCM is in the diagnostic mode. After 4 seconds, an audible warning tone will sound 3 times confirming that the DTCs have been cleared.