Hello everyone. I recently bought an '01 A8 and overall it's in good shape but I noticed that when I'm pressing on the brakes as I'm slowing down and I go over uneven road it seems as if the ABS is kicking in??? The wheels starts to shake something awful. Any ideas what this could be? Appreciate any help you can offer...Thanks!!!

 

The first thing that comes off the top of my head is a faulty brake light switch. If the switch thinks your are pushing the pedal harder than you are it will trip the ABS. Since you own an audi you should buy the VAG COM software if you own a lap top. www.ross-tech.com you just need to buy the diagnostic cable so you can communicate. Check the faults in the brake electronics and see if there is a specific fault code.

 

Thank you for the input...i'll give it a try when i get a chance...i bought this car for the wife but obviously during the test drive it didn't show...i drove it from florida to ny and during that time it happened a few times...freaked me out at first...

 

Another thing to look at is the tires, if they are getting bald they will sometimes slip causing the touchy ABS to activate.

 

wish that was the case but the tires were replaced not 2 weeks ago...i've heard that the abs sensor could be bad...wish i could get more input on this...i don't feel too comfortable with my wife driving this car and now i'm thinking about dumping it....

 

If it had a bad ABS sensor there would just be an ABS light on in the dash and the ABS itself would be disabled. Activation with little pedal effort is more likely a switch problem.
I would hate to see you throw away a very good car for a $20 brake light switch problem....

 

Right...makes senses that if it was an abs problem a light would be there or a code for that matter...is there a diy for this perhaps...part number; anything to check this out...
thanks

j

 

Oh its not really that hard, you will have to remove the panel under the steering wheel to get at the switch though. Once thats out, the switch just twists out. Pop a new one in and you're done. The switches can be a little tricky though, sometimes the brake lights won't work or they will stay on all the time. If that happens pull the switch back out, pull the thimble back out all the way and reinstall the switch until it works correctly.

 

Something simple: the wheels are leaving the road while braking which makes it 'stop' for a brief period and thus making the the ABS kick-in. Each wheel will be 'stopped' at a different time (uneven road) causing the ABS to react to each wheel differently, and at different times making the car 'shake'. I'd look into the struts going out, and, tire pressure.

Also, the ABS sensors could not be bad, but just dirty. Semi-metallic brake dust could get lodged between the sensor and reluctor ring (toothed wheel), and/or fill the gaps between the teeth, making the ABS think the wheel is going slower than it really is. I have seen the gaps between the teeth completely filled with brake dust. Rings that are rusty cause problems as well.

 

I'll try to mess around with this an see if it helps...thanks again for your help...really appreciate your time....


My first "gut" instinct was this....that there was a strut issue....what i forgot to mention was that whenever i make a turn (left or right) i hear clicking/creaking noises from what seems to be the glove box area but more likely will be the strut mount area??? close enough to be mistaken....IF it is the strut (and the noise only comes from the front right; it seems the ABS kicks in on that side as well) is there a something other then oem to put in there (if we need to replace it right!!!!) that's better....i come from bmw and if anything like it there should be tons of stuff that better then oem and better priced as well....thanks for the reply