GM Service Manual Online
For 1990-2009 cars only

Clearing DTCs for GMC Truck GMC P42 Commercial Chassis 1999

Use a Scan Tool in order to erase the DTCs in the EBCM memory. Verify proper system operation and absence of DTCs when the clearing procedure completes. DTCs cannot be cleared by unplugging the EBCM, by disconnecting the battery cables, or by turning the ignition OFF.