LEADASS

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

jon928se

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.

LEADASS

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