ABS light on when 70mph reached!! Pedal feels weird

[craggy_t]

Hi everyone,
Hopefully one of you can shine some light on this subject. When i increase my speed to around the 70mph zone the yellow ABS light comes on and remains on until I restart the car.
Also, when i'm slowing down or braking at low speeds I can feel a soft "drum roll" kinda thing through the pedal. Can hear clicking too as if the ABS is going on and off.
Any help much appreciated
1996 1.8T

 

[PaulJC84]

Will be one of you abs sensors.

Perhaps one has a fault wire or something and only gets affected when mobile.

Cheers.

 

[craggy_t]

Cheers, i'll check it out.

 

[eimajmong]

I've got a similar problem with my '97 A4.

It only ever happens when braking lightly from below 15mph.

It began shortly after I got the car (the abs and warning lights illuminated).

When I took it back the guy said he would plug it into the vagcom and see what the problem was. The problem was that he didn't! He reset the system without looking for the fault. Now I'm left with the problem and my local specialist has checked the sensors and can't find anything.

He did mention something about the possibility of a crack in the abs ring which would require taking the brakes apart, as well as my bank balance.

I've disconnected the battery overnight in the hope that the warning will be shown again but I won't hold my breath.

If anyone can help it'd be much appreciated

 

[imported_VaulterTim]

Disconnecting the battery will only help clear the fault... same as resetting it in VAG-COM. The only sure way of getting the fault to re-appear would be to wait I guess... or try to recreate the situation where you first noticed it..?

 

[mas]

The low speed problem - especially if there is no fault shown on vag-com - is probably the reluctor ring being cracked or clogged with muck.

You can do a quick check on the sensors by testing their resistance. The front ones have a connector just inside the wing, pull the rubber grommet out and the connector is accessible. The rears have a connector under the rear seat.

 

[eimajmong]

The guy at the garage has said this also but added they would have to check which obviously costs money.

I reckon I'll have to get something done coz the clunking noise is starting to do my head in and I doubt it is very good for the discs.

Thank you

 

[mas]

If the warning lights come on then they should be able to read the codes and identify what the problem is (and also if you have the abs warning light on then its prob not the reluctor ring).

If no lights come on but the abs activates at low speed, then its a reluctor ring - no big deal unless you have a quattro. The rings sit in the disks so you just have to pop the disks off until you find the faulty one (quattros have the rear rings in the cv joint) . Meantime, I found that pulling the abs fuse resulted in the abs lights coming on, beeping and a warning message (and the abs didnt work at all) but it was a much better situation because ?I could rely on the stopping distances.

 

[The911SC]

I had this on my old 97 B5. It was the brake disk itself.
The abs sensor is pushed through a hole and it picks up pulses from the brakedisk. What happens is when the brake disk becomes rusty, the sensor fails to pick it up correctly.
The vag com will tell you which wheel is the culprit.
If your disks are ok and don need changning, cleaning the area with a wire brush thoroughly fixed it short term although 'xvw' changed the disks (eventually!) after he bought it off me.
Be careful though as there are different types of disks..!

 

[eimajmong]

Got the garage to look at my car today.

Both reluctor rings at the rear are toby mangled so replacements look a certainty.

At least it waited until after Christmas to break. :-(