ABS dash warning light is on and...
#1
Pro
Thread Starter
ABS dash warning light is on and...
My brakes work fantastically but no ABS and I've got the big "!" lit on the dash. Let me preface this by telling you my brakes are a bit Frankenstein. It's an early '86 car (two piston original) that I was able to (with most of the work done by a local pro) install a four corner set of 993 TT Big Reds. We installed the 78-82 front spindles and needed a full set of 7mm spacers and My guy Ralph at Performance Plus (207)883-2656 was able to rig a bracket for the ABS sensor at the two front corners. The wires are pretty tight but the system has worked for well over a year. At my last track day I got the warning light but the brakes are unbelievable.Over the last couple of days I had Ralph try to figure the problem out.
He checked all the low hanging fruit: relays,fuses, cleaning sensors,cleaning grounds, check for power at all points, and did a resistance test at the four sensors. The right front sensor read a bit off and he suspects there may be a problem there.
Late this afternoon he reassembled everything and took her for a test ride(he replaced nothing). The warning light was out and the ABS was working fine. Two hours later I pick up the car and begin my hour drive home. We had no idea what he did to correct the problem but shrugged our shoulders and off I went.
As I drove home all seemed to be well and great speeds were attained... I got off the highway and as I applied the brakes they worked great unil I was at three MPH or so. I then got some weird squish at the pedal and a pulsing sensation(no warning light). I drove for five or so miles at 25-55 mph and really flexed the brakes: same squish/pulse just before I came to a complete stop. At the second to last light the warning light comes on and I have the best feeling brakes you could ask for. I push the car hard at low speeds and she stops on a dime, I have a warning light.
Can anyone tell me WTF is happening? Is there a greater problem or should I just disable the ABS system? Thanks, Brian
He checked all the low hanging fruit: relays,fuses, cleaning sensors,cleaning grounds, check for power at all points, and did a resistance test at the four sensors. The right front sensor read a bit off and he suspects there may be a problem there.
Late this afternoon he reassembled everything and took her for a test ride(he replaced nothing). The warning light was out and the ABS was working fine. Two hours later I pick up the car and begin my hour drive home. We had no idea what he did to correct the problem but shrugged our shoulders and off I went.
As I drove home all seemed to be well and great speeds were attained... I got off the highway and as I applied the brakes they worked great unil I was at three MPH or so. I then got some weird squish at the pedal and a pulsing sensation(no warning light). I drove for five or so miles at 25-55 mph and really flexed the brakes: same squish/pulse just before I came to a complete stop. At the second to last light the warning light comes on and I have the best feeling brakes you could ask for. I push the car hard at low speeds and she stops on a dime, I have a warning light.
Can anyone tell me WTF is happening? Is there a greater problem or should I just disable the ABS system? Thanks, Brian
#2
Addict
Rennlist Member
Rennlist Member
Parital activation of the ABS at very low speeds (when you aren't actually lokcing a wheel) indicates that ABS brain thinks that one or more sensors is not registering rotation of the wheel.
This could be due to dirty toothed rotors, a failing sensor or dubious wiring.
This could be due to dirty toothed rotors, a failing sensor or dubious wiring.
#3
Pro
Thread Starter
Thanks Jon, I'm looking at one of the wheel sensors (front right) and will replace next week. I hope this does it, if not I fear it's the wiring. Can you cut or repair the wiring? I'm wondering if there are any changes to the wiring at at it could change its resistance and cause a problem? Thanks again, Brian