I'm having ABS activation whenever I brake below 15mph, bit of a nuisance when crawling in traffic and having to apply the brakes.
Removed the ABS relay and went for a short drive (not on main road) and the ABS activation / brake judder stopped, so to my mind that ruled out any air in the brake hydraulics.
After a few applications I lost the brakes completely - fair enough.
Replaced relay and drove without ABS fuse, again no ABS or brake judder below 15 mph but at least the brakes didn't go West.
Strangely the ABS compressor activated every second application of the brakes with the ABS fuse removed, whereas with the fuse and relay in it behaves normally - i.e. cuts in after 4 or 5 applications.

I assume the fault is with one of the ABS sensors - your thoughts ?
The 3 amigos don't show under normal driving conditions and the ABS light goes out after a few MPH as it should
2001 - 2001 P38

Certainly sounds like one of the ABS sensors is playing up and assuming one wheel is locking. It could be a faulty sensor although I would expect that to bring on the warning lamp. It could be a sloppy wheel bearing so the sensor to reluctor ring gap is changing under braking?

Thanks, no warning lamp at all with ABS relay and ABS fuse in situ.

As a footnote: when I removed just the ABS fuse the brakes were excellent, but the ABS and TC lights stayed on..
Why would the TC light come on if I'd taken out the ABS fuse ?

I think I've sussed it - ABS gives traction control

Theoretically the air gap between ABS sensor and reluctor ring can self open up reducing the signal and causing problems. Seems unlikely to me as I've never met one that could be removed without destruction. They do self adjust after a new one has been put in all clean and nicely lubricated but after a few years ...

Worth an inspection of the wiring loom and connectors. I'd not expect troubles with the sensor cable to main loom connector as that is very secure and well protected but advisable to check.

Low speed only issues certainly sound as if the sensor output isn't high enough so basically air gap, connectors or wiring to suspect.

Clive

Clive603 wrote:

Theoretically the air gap between ABS sensor and reluctor ring can self open up reducing the signal and causing problems. Seems unlikely to me as I've never met one that could be removed without destruction. They do self adjust after a new one has been put in all clean and nicely lubricated but after a few years ...

Mine popped out incredibly easily, and went back in again with no drama. Not like the bloody hub bearing carrier...