Posted by Charlie on February 03, 03 at 13:21:12:
I have a 1997 Suburban 1500 with 4wd. It has developed a problem where as you slow to a stop, during the last 3-5 mph the anti-lock brakes engage even on good surfaces. Needless to say, that's a bit nerve-racking when you're in traffic and the ABS suddenly demands a few more feet of stopping space! I was wondering if anyone had any experience dealing with a similar problem or any thoughts on how to fix it.
Here's the problem in more detail. Pulling the fuse on the ABS system eliminates the premature ABS. Obviously it's not ideal driving around without ABS, but this does help narrow the possible causes.
Hooking the car up to a computer while driving reveals that at low speeds the front wheels and rear axle (3 sensor system) "think" they're going different speeds. The ABS interprets this as a skid and activates the system.
I've been told by one mechanic who was a bit too enthusiastic to spend my money that the solution was to replace the speed sensors on the front wheels. This, he confided to me, required the replacement of the entire hub at $500 a wheel. I'm not biting until I've explored other options.
Right now, my mechanic and I are a bit stumped on how to go about it without some expensive exploratory work. Thoughts I've heard range from dirty sensors, bad hydrolic fluid, and even the valve that regulates front/rear braking force.
Has anyone encountered this problem? How did you resolve it? Any help would be greatly appreciated!
Thanks in advance,
Charlie K