ABS brake problem?A4 Avant 1.9tdi 1998

[desh]

I've had problems in the past with ABS light on, apparently the sensors were trying to read a loose ring. This resulted in a hideous grinding, lack of braking efficiency and the effect of the pedal pushing back at you when you brake hard. Eek!

I got that sorted and only had it mildly (now and then) when pulling up to a stop, until now. Whether connected or not (after replacing the rear caliper seal and piston) it's back. BUT no ABS light and it only occurs on violent emergency (test) braking. If I firmly brake over approx 200yds (ish) it doesn't occur. Hmmm.

But when it does...(!) it's a bit disturbing.

[Guest 2]

Get it scanned for faults!

[zollaf]

sounds like an air gap too large. the distance between the sensor and the ring. if its too big the sensor kicks in and then the abs does its thing, thinking a wheel has locked. you can check this in live readings, seeing which sensor drops off to 0, or by connecting an oscilloscope to each sensor and seeing what happens.