ABS Brakes pulsating at low speed stops intermitantly

[wdchparks]

I have a 1999 C2500 Chevy Silverado extended cab
On some slow speed stops the ABS kicks in and makes it hard to come to a full stop scary. There are no leaks in the system. The ABS light has come on, on the dash off and on. Kid in college kid getting braces divorced, need to home repair. I thought I saw a post that you can shut off the ABS system not the real fix but safer until I can figure it out. Any help appreciated!!!

[Tech II]

There is a TSB matching these symptoms...not sure if it includes your year.....basically, there is a rust buildup under the ABS sensor(increases the gap)....you remove the sensor, sand down the mating surface, add grease/rust inhibitor to the surface and wipe off...re-install the sensor...do Both fronts....

Unfortunately, sometimes the sensor can be stuck in the hole and is damaged on removal, and then it has to be replaced....but the main thing is to clean down that mating surface, even if a new sensor is installed....

[j cAT]

Originally Posted by wdchparks

I have a 1999 C2500 Chevy Silverado extended cab
On some slow speed stops the ABS kicks in and makes it hard to come to a full stop scary. There are no leaks in the system. The ABS light has come on, on the dash off and on. Kid in college kid getting braces divorced, need to home repair. I thought I saw a post that you can shut off the ABS system not the real fix but safer until I can figure it out. Any help appreciated!!!

the problem you have is most likely one or both front hubs are in need of replacement. removal of the sensor that is mounted in the hub assy should have blue grease . if this is a rusty brown color then you know that the grease seals of the hub assy bearing have failed and water/rock salt entered damaging the speed sensor pick up from reading the proper speed. at slow speeds the sensor voltage is low at first then you get this soon it will get much worse and you will not stop . I have done this many times over 2000 silverado owner..

only use timken bearing hubs .....

[j cAT]

Originally Posted by wdchparks

I have a 1999 C2500 Chevy Silverado extended cab
On some slow speed stops the ABS kicks in and makes it hard to come to a full stop scary. There are no leaks in the system. The ABS light has come on, on the dash off and on. Kid in college kid getting braces divorced, need to home repair. I thought I saw a post that you can shut off the ABS system not the real fix but safer until I can figure it out. Any help appreciated!!!

this was a recall on my 2000 silverado by GM . what gm tsb did was to re-seat these sensors on the hub mounting surface and they would also clean the pickup portion of the sensor. doing this would make the ABS work until the warranty ended. this was used by GM to avoid replacing the OEM defective hub assy . these assy had defective grease seals on the hub bearing. many times I have seen no metal at all left . just the rubber seal . meaning you could actually see the bearings like no seal was there ....

In the rust belt I know of these requiring replacement every few years with use during winter snow events in the operation of these vehicles. timken appears to last the longest .

I would remove the 60 amp abs fuse until you fix this or you will get smashed.

[wdchparks]

Thank you to all. I had a feeling due to the age that rust had a part. The truck has cost me few dollars over its life.

Pulling the ABS fuse will not interfere with regular breaking until I repair the sending units?

It is bad when it kicks in you just keep rolling with the pulsating brakes. Like all of us time and money are not my friends.

[j cAT]

Originally Posted by wdchparks

Thank you to all. I had a feeling due to the age that rust had a part. The truck has cost me few dollars over its life.

Pulling the ABS fuse will not interfere with regular breaking until I repair the sending units?

It is bad when it kicks in you just keep rolling with the pulsating brakes. Like all of us time and money are not my friends.

the front hubs [new] come with sensors as they must be properly calibrated to provide the proper voltage levels to be working properly.

removal of the 60 amp ABS fuse will disable this function . you will get an ABS LT on and then you will have problems at inspection time .

[kenman1717]

its possible its your tires. used to work at a gm dealer fixed a few of these, did the reseating of the sensors, cleaning rust, replacing sensors, replacing hubs. sometimes this worked, other times it turned out to be the rolling circumference of the tires, being different side to side. if you have different brands front to back, a possibility there or if there is a significant tread depth difference between front and back tires. with most vehicles this isn't an issue, but with some the abs kicks in at low speeds.
oh and make sure they are the same size front to back, this could be it as well.

[ken_man_1]

I have removed the 60 amp fuse on my plow trucks, and it fully disables the ABS. The guys prefer the no ABS when plowing.

j cAT is right on with the possibility of sensors and hubs.