A4 luvr

I have a brake issue and need help. Almost every time I brake to a stop, the car jerks significantly for an instant when it slows down to about 20 kph. Its just an instantaneous jerk once when I'm almost stopped. It feels like the ABS is cutting in for just an instant. I have not determined if its just 1 wheel or all 4. There do not seem to be any trouble codes registered, no ABS light on dash. Wheels sensors seem to be working fine (checked with Snap On scan tool.) Anyone know of this problem? Any help appreciated.

accord96

I just started to get this issue too, right after i replaced my front break lines?

Havent been able to get to the mechanic since it was done. any ideas?

A4 luvr

My issue started some months ago w/o having any work done. All my wheel sensors seem to be OK so I'm thinking the ABS controller altho if this unit gives trouble it should give the ABS warning light. I've heard these units are very expensive. I believe these units are 1/2 mechanical (hydraulic) and 1/2 electronic. When there is a problem with the controller, 9 times ouit of 10 its the electronic portion and these can be bought from BBA Remanufacturing Inc for about US$200. My mechanic is checking further into what might be the problem. I'm going to try other forums also to find a solution. Someone else must have had this problem. BTW when my 86 Accord finally went off to ice racing school, I bought the Audi. PS site will not allow me to post web site of BBA yet-need 5 posts before I can. Google them.

wailshark

Strange that there is no codes, usually the ECU throws one if something like the sensor is failing.

The sudden jerkiness does sound like it could be a problem with the ABS control module but also you may want to check all the lines for kinks/leaks.

Corrado_Guy

The most common issue I have seen with this is dirty ABS sensors or defective ones. An easy test is to unplug the connector from one of the ABS sensors which will disable the sensor (with a code & light) and then try stopping again. If the problem stops then it may just be a dirty sensor or a damaged ABS ring.

I've seen this before and it can be due to the ABS kicking in thinking one of the wheels is slipping. I've also seen the same thing with the traction control if equipped, it sees it as one wheel slipping then puts the brakes on to slow that one wheel.

If it is an ABS sensor you should try cleaning it first and see if that fixes it. The code for a sensor is thrown when the base signal for the sensor goes out of the monitored range but it doesn't mean the sensor is bad. If the sensor is covered in crap the signal monitored by the ABS computer is still within specs but it will not behave as it should.

If the gap between the sensor and the ABS ring is too big it will also be unreliable and you can get these funny reactions when braking. Also, sticking calipers can also cause this sort of behaviour so make sure your brakes aren't hanging when stopping.

Black_RS4

is it a possibility the lines have not been bled properly and there is air in the system?