ABS keeps cutting in

[220bhp]

I did the near side wheel bearing on my s6 yesterday. and desided to do the front brake pads at the same time,now the ABS keeps coming on, not the light ,but the actual ABS, and it seams to be more on the driver side.the yellow break light is also on.
I have checked all the censors and they are all connected and every thing seem to be ok, so has anyone any idea as to what could be wrong,


Cheers Lou

[pastures16]

has the pads got wear sensors fitted could be faulty sensors or broken wire

[NoNonsense]

Sounds to me like you need to clean the sensors themselves. The sensors are magnetic, and they pick up all the brake dust (metallic) which will cause that "bonging" noise just before you come to a complete stop.

if you can remove the sensor without damaging it, then clean them up.

Another thing I see a lot where I live is corrosion will get on the teeth (at the end of the axle) and cause the ABS to engage.

Good luck!

[philS2]

quote 'Another thing I see a lot where I live is corrosion will get on the teeth (at the end of the axle) and cause the ABS to engage.'

i had this problem.IIRC,i just got a hacksaw blade and cleaned in between the teeth.and a small screwdriver for the one i couldn't be bothered to take off.

[audiman]

Normally the thing that causes this type of problem is the air gap between the sensor and the rotor (ABS ring). If the air gap is too large you tend to get the ABS cut in as your almost stop. This is due to the ECU seeing different speeds on both front wheels (or rear). If you have a later ABY then there are some ABS diagnostics you can access with VAG-COM to confirm this. Just take a look at the wheel speeds as you come to a stop. I suspect 3 will be the same and one will show a different speed.

And I put my money on it being the one you just did the bearing on! The shock of moving bearings can often have this effect. Just adjust the sensor so its about 0.5mm away from the ring. It it moved when doing the bearing then chances are it will move to adjust it.

HTH

[220bhp]

As usual, great information,many thanks for your help,I will check it out and let you know how I get on.What would I do without you all Lou

[220bhp]

I have taken it all apart , clean the censors and reassembled, the abs still comes on as you come to a slow stop.Tom the car is a 1995 s6 avant,don't know if that makes it any differant to the aby set up,but I can't see what you mean buy adjusting the air gap, how do I do that.


Many Thanks Lou

[audiman]

you need to use a feeler gauge. get it between the end of the sensor and the rotor on the CV joint. that is the air gap. These need to be the same on all wheels. set it to about 0.5-1mm If you have too large an air gap you get the problem as described. If you still dont get it sorted then you will need to get some diagnostics on the car such as VAG-COM and check the system out. Check the basics first, if that doesnt cure it then it needs deeper investigation. It doesnt sound like a component failure as the light is going out on start up. So my best guess over the net is the air gap adjustment.

[audiman]

The sensors "should" move in there holders, they are tight, but they should move a bit. Unless they are seized solid, which wouldnt surprise me on a 12 y/o car