Abs Kicks In When Almost At Complete Stop

famouslee99gt · November 20, 2009

I have a 1999 Chevy Silverado 1500 Z71 and am having issues with my ABS. When coming to a stop, the ABS will kick in when under 10ish mph. I started to happen after I changed my driver front wheel bearing. It was a cheap Ebay bearing, so, now, about 3-4 months later, I bought a new wheel bearing and installed it today to see if it changed. Nope. When I changed it a couple months ago, the ABS & Brake light would come on but reset when I would shut the truck off. The ABS pump is not having the typical issue where it runs non-stop, but it kicks in for no reason.

jljhlhl · November 20, 2009

I'm experiencing the exact same problem. Almost caused me to rear end someone yesterday as I was almost stopped when it kicked in and then I couldnt stop anymore and almost rolled right into the back of him.

Theres a TSB out there 03-05-25-007d that says its caused by an increased air gap between the wheel speed sensor and hub reluctor ring due to rust and debris build up on the sensor mounting surface.

Hopefully someone can post the TSB, for some reason I cant copy paste it.

lilnotts · November 20, 2009

my bros old 00 silv had the same issue, he ended up replacing his wheel speed sensor

jtupper · November 20, 2009

I have been having a similar problem. I have been noticing that if I hit a bump while on the brakes, the ABS will kick in almost like I lose my brakes for a second, but I can feel the pulsation in the pedal. Then the brakes will "catch" and it's like I hit the brakes too hard all of a sudden. I also get the ABS and brake light from time to time, but it always resets once you turn the key off like the OP described.

georgecdisc · November 20, 2009

On my '98 Silverado the mounting surface below the sensor began to corrode, causing the sensor to lift. It only lifted like a millimeter, but enough that the sensors would have issues reading. I never had an ABS light go on, but I had issues at stopping speed where my ABS would go off (pulsating pedal). This was because my front sensors could not get a good reading, didn't match with the rear wheel speed, thus a time ABS should engage. I used a wire brush to clean up the mounting surfaces, worked like a charm! Before doing this I put in a paper towel to the hole to plug it up so debris wouldn't go inside it.

09Jimmy · November 20, 2009

Swhitney is right. The problem is called "unintended low speed ABS activation". There was a recall for trucks in the "rust belt". Undo the torx screw that holds the ABS "reader" to the hub and pull it out. Put a piece of paper towel in the hole and use some emery cloth to remove the corrosion on the mounting pad. Just a millimeter of corrosion will hold the reader far enough away from the sensor to cause low speed activation. Put some grease on the mounting pad and tighten the reader back to the hub. Problem solved.

Irv · November 22, 2009

On my '98 Silverado the mounting surface below the sensor began to corrode, causing the sensor to lift. It only lifted like a millimeter, but enough that the sensors would have issues reading. I never had an ABS light go on, but I had issues at stopping speed where my ABS would go off (pulsating pedal). This was because my front sensors could not get a good reading, didn't match with the rear wheel speed, thus a time ABS should engage. I used a wire brush to clean up the mounting surfaces, worked like a charm! Before doing this I put in a paper towel to the hole to plug it up so debris wouldn't go inside it.

My 97 would get like this too, did as swhitey did above and cured it, for a while then had to re-do it about every year year and a half.

GasHog369 · November 22, 2009

i had this same problem with my truck... ended up being my abs speed sensor... When my mechanic went to take them out and clean off the rust on hub they both broke... $230 each side later it drives like new again... but was a costly repair... I could have go the sensors cheaper online but my truck was in shop with both wheels off / calipers.. and i needed it next day so the stealership was only option

FlamesZ71 · November 23, 2009

I had the same issue, my Passenger side was already pooched, and I probably helped the issue along when I pulled the sensor out and part of it stayed in the hub assembly. Luckily, my shop had a used sensor for $30 bucks, plus an hour of shop time.

If you feel like it, CAREFULLY pull the sensors out, and go from there.

GasHog369 · November 23, 2009

If and when you pull the sensors out, be prepared to buy new ones... I trust my shop , good friend of our family, and both sensors broke when they tried removing them.. Then the problem was the plastic piece stayed inside so it took them even longer to remove it.. Just prepare for the worse...

jblakeney · November 23, 2009

I have a 1999 Chevy Silverado 1500 Z71 and am having issues with my ABS. When coming to a stop, the ABS will kick in when under 10ish mph. I started to happen after I changed my driver front wheel bearing. It was a cheap Ebay bearing, so, now, about 3-4 months later, I bought a new wheel bearing and installed it today to see if it changed. Nope. When I changed it a couple months ago, the ABS & Brake light would come on but reset when I would shut the truck off. The ABS pump is not having the typical issue where it runs non-stop, but it kicks in for no reason.

Any chance you have the ABS codes?????? Cxxxx.................. Could be the control module

Jbo

famouslee99gt · November 23, 2009

I pulled the sensor on the passenger side and cleaned it up, came out ok, and wasn't all that dirty. It had 3 shims on it, in which i left all 3 on, but cleaned them all up. Before I even left the driveway, abs kicked in again. I pulled the fuse until I can get it to the dealer because I have had many close calls and it's getting annoying. Last night when I came home from work, just perfect, no issues....Today, I drove 1 mile over to my grandparents and it did it about 2 or 3 times that I had to slow down to stop.

GasHog369 · November 25, 2009

those are the same symptoms i had... Did you clean rust off hub? if so then you need new sensors... If you can , avoid going to dealer for them and get them online... i needed my truck right away and only option i had was dealer and paid dearly for it

famouslee99gt · November 25, 2009

The driver sensor is brand new because it was with the bearing. Even the passenger side bearing/sensor is just over a year old and looked just fine. Unless it's my rear abs sensor, which is in the rear axle or transfer case, I'm not sure. I'm getting tired of screwing with it. The dealer can tell me what's wrong with it, because I give up

Pumper · November 25, 2009

When I owned my 2001 I got a recall notice for this problem. I didn't have the problem so I never took my truck in, but I am pretty sure that GM was going to cover it. I might be worth while for you guys to look into it by calling the dealer.