Antilock Brake issue help

Murphy625 · March 24, 2017

Hi folks,
I have a 2000 GMC 2500 4wd truck.. (SLE)

Every brake line on the vehicle has rusted out and I've replaced them one by one.. I've actually gotten quite skilled at what to do when I my vehicle's brakes fail in traffic.. (Practice makes perfect eh?)

The truck seems to have developed a strange problem with the brake system.

Whenever I come to a slow stop, the anti-lock brake system kicks in and makes a strong groaning sound and pushes back on the pedal. This only happens when the truck is just about to come to a complete stop.. It does not happen during the initial braking from higher speeds.. only when the vehicle is under 5 mph or so.

If I smack the brakes from highway speeds, the vehicle stops fine.

I also notice that it sometimes wants to pull to the right and it makes me think the problem is in the left front brake somewhere.

This groaning started off very intermittent about a year ago.. It would act up once occasionally when I drove the vehicle someplace. Now the problem has gotten worse and it does it whenever I stop.

I should note that when this issue occurs, the vehicle WILL NOT stop unless I pump the brake pedal once.. then it goes away and the vehicle stops as normal.

My brake pedal is NOT squishy and I seem to have good strong brakes when I'm decelerating from highway speeds.

What in blazes is going on?

SILVER SLED · March 24, 2017

Take the front wheel speed sensors out of the hubs and clean the surface on the hub, and if the wheel speed sensors didn't crumble taking them out put them back in. If they did crumble then put a new sensor(s) in. What usually happens is the hub rusts, pushing the sensor up away from the the hub and causing a poor reading from the sensor at low speeds. It will read 0 mph and activate the abs.

arcasey · March 24, 2017

Wheel speed sensors most likely. If its pulling to the right then the left wheel is where the low speed abs activation is occuring. I just had this same issue on my old truck. As SILVER SLED mentioned you should try cleaning the wheel speed sensors first and if you are still having issues then replace the sensors.