The ABS brake system in a GMC vehicle uses a sophisticated ABS module to sense wheel speed. If the vehicle’s wheels stop moving while brake pressure is being applied, but the vehicle itself is still moving, the system identifies this as a skid and automatically releases brake pressure to prevent the brake system from locking up. Instead, the ABS system will pump the brakes to provide better control over the vehicle for the driver. If you suspect you are having trouble with the GMC ABS brake system, you should troubleshoot the problem to verify whether there is a failure in the system.
1. Open the fuse panel underneath the dash.
2. Remove the fuse for the ABS system with the fuse puller located on the dash panel lid. Inspect the fuse. If the fuse is popped, then you’ll need to replace it. If it is not popped, then put the fuse back into the ABS fuse slot.
3. Turn the steering wheel all the way to the right.
4. Check behind the wheels on the ground with a flashlight. Check to make sure that the wires running to the wheel hub assembly (these are the ABS wires) are not damaged in any way.
5. Turn the ignition to the “II” position and check the ABS dash light. If the ABS dash light comes on and stays lit, and none of the ABS wires are damaged, it is likely that there is a partial failure in the ABS sensor.