ABS come on at low speeds why?

BEN MARINCHEK

MEMBER
1999 CHEVROLET TRUCK
5.3L
V8
4WD
AUTOMATIC
150,000 MILES

Both ABS and brake lights are on(currently ABS fuse is pulled to prevent the problem from happening)

Problem:
Brakes work normal when stopping at high speeds. As soon as slowing speed hits five to ten mph brakes stop working and engage disengage irregular. Very dangerous yes. That is why fuse is pulled to disable ABS.

I thought it was ABS sensor changed front and did not change anything. Thinking it is computer module.

Could it be something else?

1 Reply

STEVE W.

MECHANIC
12,960 POSTS

Ninety nine percent of the time this is a bad sensor or sensors. But to avoid a lot of extra work, you need a scan tool that can read the live data from each sensor and tell you which one(s) have a problem. The problem is that at least one sensor is dropping out earlier than the others, so maybe the right front reads three mph but the left reads zero, that will set off the ABS.

The usual cause is rust between the hub and the sensor. For that you remove the sensor, plug the hole in the hub with some cotton, then remove the rust from the hub, apply a thin coat of paint, then some silicone to the sensor, remove the cotton and install the sensor. Then you brush some plasti-dip type coating around the sensor to seal out moisture/crud.

It sounds like you may have a wheel speed sensor that is out. These videos will help us find the problem.

https://youtu.be/rTtAnsOlZU4

and

https://youtu.be/Pb6nXV-iamI

and

https://youtu.be/ANWVTh2RQoQ

and

https://www.2carpros.com/articles/abs-warning-light-on-easy-repair-guide

Please run down these guides and report back.