ABS randomly engages

[b4black]

I having trouble with the ABS. It randomly engages, even under light braking. It seems to have a bad wheel sensor, but it doesn't trip the red warning light. It's been this way for a long time and will be covered under warrenty, but the dealership says they can't fix it without the warning light coming on. Until it does, they can't telll which sensor is bad.

Anybody else run into this? Thanks.

 

[lautinjr]

Skip the dealer it's to expensive. Yes it will store the fault code in the ABS unit and can be identified with out the light being on. Most of the ABS problems out there same symptoms as what you describe, and usually caused by a wheel bearing. If you can't pull the code your self check the bearings at each wheel for play or slack. Also do a spring test where you place your hand on the spring and spin the tire or have some one else spin the tire. You can feel the bearing grinding internally through the spring it's a great conductor for vibration, and the best way to find a bad bearing that doesn't have play yet. If you feel a bad bearing it's more then likely your ABS fault still worth getting the code checked.

Need to check mine also no ABS fault just sounds like a bearing lately

 

[b4black]

It's under warrenty, so it will be free at the dealeship. It never trips the light, so there are no codes to check. That's why the dealership doesn't know which sensor is bad. (I think they should start with one and go from there.)

Good suggestion on the wheel bearings. I'll check into that.

 

[lautinjr]

The light doesn't need t be on to pull the codes it saves Data. They just won't repair if it's not a current failure. Sometimes it's a pain dealing with dealers. Free is free though. Mines in at the deale now getting the windows fixed.

 

[b4black]

There are no codes. That's the problem.

If it never trips the light, because it never recognizes a fault, then there is no code to report. If they could pull a code, they would replace that wheel's sensor.

 

[rockymountain]

Have you checked the tires? all inflated the same and wearing evenly?

 

[lautinjr]

I miss read your first post sorry. More then likely the Jeep hasn't had it's brake fluid serviced regularily this can some times cause build up on the ball valve in the ABS pump. It's spring loaded to keep fluid from bypassing if crud builds in there sometimes the ABS will engage uncalled for. I had this happen to a Ranger once. The suggested repair was to replace the unit, instead going off a World class Techs suggestion we flushed the system very thorowly with a full Synthetic brake fluid to clean it. Not sure why he wanted to use full Synthetic, but it worked problem went away. The unit is still in service today delivery truck. We used over the counter Full syn Valvoline fluid put about 64 OZ's through the system. Not sure if ti's the same problem, but worth a try and cheap fix if it is. If not could probably have used it anyway.

 

[tjkj2002]

This very same issue is very common in GM fullsizes and it is bad unit bearings.They get corroded inside and play hell with the ABS at low speeds but never trip a code or ABS malfunction.

Pull the ABS sensors,very brittle and most likely will break on removal,and check inside the hub for any signs of corrosion.Best bet is just to replace both front hubs and be done with it.Can be done for about $300 with Timkin bearings and about 30mins of work,just need a E14 socket and a 35mm socket.