Vag-Com for my ABS???

[rdguy]

I have been having trouble with the ABS activating on dry pavement coming to a stop. I did not have the flashing brake light as described on the Bosch ABS system failure. So today I disconnected the ABS and now I have the ABS light as well as the brake light flashing. Would clearing the codes clear the problem or is it a module failure? 98 A4 Quattro.

[spidey9999]

If the ABS is activating when you are just about completely stopped, one of the ABS sensor rings on a wheel hub is likely cracked. Rust builds up on the hub, expands and eventually splits the ring.

This happened to me ('01 A4) and dealer said whole hub needed to be replaced as the ring isn't available separately (lots of $). I found a VW/Audi repair shop who had figured out how to remove the ring, clean up the rust, carefully weld the ring back together and reinstall it . Cost me approx. $200 for that and it has worked fine for more than 100k km.

HTH

[rdguy]

Where is this shop located? Are they good?
Rick

[Jurjen]

If the ABS is activating when you are just about completely stopped, one of the ABS sensor rings on a wheel hub is likely cracked. Rust builds up on the hub, expands and eventually splits the ring.

This happened to me ('01 A4) and dealer said whole hub needed to be replaced as the ring isn't available separately (lots of $). I found a VW/Audi repair shop who had figured out how to remove the ring, clean up the rust, carefully weld the ring back together and reinstall it . Cost me approx. $200 for that and it has worked fine for more than 100k km.

HTH

I had this on my s4 too - ended up replacing both hubs - they already been welded by the previous owner i guess.

[AudiLife]

This has happened to me and it ended up being one of the ABS wheel speed sensors, had someone log the readings for me to tell me which one it was. Rust easily forms on the sensor and the ring itself. If you are a DYIer pull out the sensors and clean them up and reinstall, at the same time you can look down the hole the sensor sits in to inspect the ABS hub ring for cracks. If that doesn't work then get someone to log the speed sensor for you, I could do it for you but you'll have to wait till the week of Sept 8th.

[rdguy]

I am not sure what you mean by log the readings to find out which one. Is that done through the vag? Do the sensors just pull out? I tried pulling one a few weeks back but it did not budge, I was afraid of breaking it so did not force it.

[AudiLife]

Yup, when I say log them I mean log each individual ABS speed sensors, they should be reading the same speed +/- 1Km/hr I think, anything above that and the ABS will go off when slowing down. The Sensors do just pull out in a perfect world, but given it's not they are mostly likely rusted in there and a bit of force is required. Either that or you can spray a lot of liquid wrench on it and let it sit for a while to loosen up the rust. If that doesn't work you might have to pry them out which is not uncommon, I actually had to destroy/tear one of my sensors to pieces and chisel out the left over rusted bits.

[headshok2002]

You can buy the rings separately... Try an axle rebuilding shop.
I had this issue and was able to buy some rings separately. Can't remember what I went through... but yeah... I ended up getting them. :P

[spidey9999]

Where is this shop located? Are they good?
Rick

Total Mechanical Services in Orangeville. Very experienced VW/Audi repair shop.

Johnny is the owner - say Bruce referred you.

[rdguy]

This process is slow and tedious for me as my laptop does not have the correct port for Vag Com, so I have to have my wife bring her laptop home to do it. I managed to get into it tonight, but am unclear on how to log the ABS sensors?? I found the ABS module, but wonder what to do next? DO I drive the car to get readings? any help is appreciated on how to do this.
Rick

[AudiLife]

Follow link below from AW, as for the fields not sure which one corresponds to which sensor, but it's nothing a little searching won't answer.

http://forums.audiworld.com/a4/msgs/2393442.phtml

Edit:

I believe this is the answer to which field belongs to which wheel sensor.

http://forums.audiworld.com/a4/msgs/2393444.phtml

[rdguy]

I did this..but the readings I saw were the speed I was going, and all 4 were the same. I was hoping I did not have to pull axles out to check the ring. More suggestions are always welcome.

.Go into the Brakes module and chose block 001. It has four fields displaying speed reading from each of the ABS sensors. Just drive off keeping your speed below 10 mph (won't read above that speed) and see which sensor shows 0 or value way different from the others. That's your bad guy.

[Dubzilla]

dont know if anyone has mentioned this.. but it could also be your ABS Module.. working @ my dealership i have had to replace those things 100 times over.. symptoms are usually when your trying to brake from under 20.. it starts kicking in the abs..

try the following.. drive your car @ 30km/h then try stopping normally.. does it do it ?
now try stopping the car with the e-brake does it do it ?

if it does it with the normal brakes but not with your e-brake its the module that fugged.

just sharing my experience.

[rdguy]

I was looking at that side of it initially, but then got on to the sensor side of things. Is there someplace in the GTA to have the module repaired resonably, or am I better to send it south of the border for repair?

It does it at the low speeds only coming to a stop, seems fine at the higher speeds. (above 30) The first time it ever did it was pulling into my driveway.

[AUDI-TECH]

your saying the abs is very sensitive?try pushing the front sensors back in.They back out sometimes causing a weak (intermittent) signal.5 minute fix.

DCB Automotive
400/Finch
141 Oakdale rd. m3n 1w2
416 857 4873

[rdguy]

I believe the front sensors may be seized. I tried gently with a wrench on the end but that seems to have caused a Failure code "open to short" so i assume there are wires there that I may have twisted , shorted, broken etc.

So how is the best way to remove them if seized? Penetrating oil, heat, vise grips on the metal portion?