I have a 99 Chevy silverado 1500 4x4 with the 5.3. Both the ABS and brake lights are on. I bought the truck about a month ago, and I noticed that both ABS sensors are unplugged on the frame in the eng compartment. I was wondering how to troubleshoot the system to find out what is bad. I am assuming that the previous owner unplugged them because of a fault in the system. I have not tried to plug the in, but I will start there.

Any help would be great.

Thanks,

Jesse

 

After you plug them in, if you still have a light and the following symtom try this.
Symptom; while slowing with the brakes on at approx 15mph the ABS activates and the pedal drops.
Pull the calipers and rotors to access the front ABS sensors. Remove the socket head retaining screw and gently remove the sensor. If you are lucky the plastic sleeve will come out but if it doesn't just be carefull not to damage the windings on the coils. With the sensors out, clean the ounting surface where the sensor was screwed into. That surface rusts and lifts the sensor away from the reluctor and throws a fault. You will proobably need to file that surface to clean it. Carefully replace the sensors.
Unrelated but while you have the brakes apart, make sure the pads float freely in the caliper bracket. The brackets rust behind the stainless steel hardware and pinch the pads so tight that they can't move.
Bob