This is an odd ABS question, my car is a 1997 A4,2.8L, 12valve,Quattro, I have read a million posts about resoldering the ABS unit in cars that get the ABS+BRAKE light that FLASH plus the 3 beeps, my car does not do this, also my car does not have the same BOSCH unit as these cars. My fault is when you start the car you "a"...feel the ABS pump kick in...."b" no lights are "on" in the dash......."c" when driving down the road approx. half a mile BOTH ABS & BRAKE light come on SOLID....no beeps!........The car can run for HOURS with no lights coming on(when sitting at idle), but as soon as the car starts moving(within 1/4 to 1/2 mile, both lights come on and stay on)
I have tried starting the car(no lights on) in a dirt road, accelerate quickly...hit brakes....NO ABS(even with lights out).....so it doesn't matter if the lights are on or off(ABS does not work)...I have NO ABS, and NO flashing lights or beeping sounds, I checked about the BOSCH units needing re-soldering but it was NOT about my unit.
Sorry, I don't have VAG-COM or an ABS scanner, only a regular engine light scanner.
My ABS/EDL unit..... I can't remember if it is 5.3 or 5.1 or 5.0, but the "brake lines" on the ABS unit enter and exit from the SIDE of the unit and NOT the top.(I checked with a company online that does rebuilds, and mine isn't listed)
Any ideas would be appreciated....likely I'm guessing I will need an ABS scanner or VAG, but if someone has heard of this and might know the answer, that would be great!!

 

Gotta scan for codes.

 

You have Bosch 5.0, which cannot be repaired if it has a failed ABS computer.

 

The symptoms you are describing are very similar to the symptoms I had with my car. If you don't have any of the beeps and the ABS and Brake light only come on once the car starts moving then it is most likely a bad sensor. Usually, but not always, a bad ABS unit causes the ABS/brake light to come once the ignition is turned on along with some beeps. In my case it was just a dirty sensor and I cleaned it(and the rusty ABS ring around the CV joint) while I did the bearings and front end control arms. It is really advisable to get a VAG-COM because it will tell you what sensor is bad and if there is anything else wrong.

If you can't get a VAG-COM go to each wheel and pull out the sensor and thoroughly clean it with a lint free cloth and rubbing alcohol and inspect the wiring and put it back in. Another thing you can do is get a volt meter and set to measure DC volts. With the sensor firmly seated in its slot turn the brake rotor by hand quickly and meter will show a very slight induced voltage. Turn the rotor the other direction and the voltmeter will show negative volts if the sensor works properly.

Seriously though, get a VAG-COM because it will make it much easier to diagnose what the problem is and much more accurately diagnose it. For starters just cleaning out the sensors and putting it back in should give you a slight idea about your ABS problem. Good luck and don't forget to report back the findings.

 

>>>>>>Thanks for the reply, the car did have front end work done prior to me buying it (they replaced all upper & lower control arms) So I should definately start looking there. I know the rear sensors are good and clean because I recently replaced the rear wheel bearings and thoroughly cleaned everything. Thanks again, I'll keep you posted with my findings.

 

This ABS problems sucks as lots of people are having the issues with it. Audi should recall this or give as parts for free.

1996 A4 2.8 quattro -- BOSCH 5 ABS/EDL

1 Fault Found 00302 - ABS Solenoid Valve Relay (J106)
35-00 - -"

Checked all ABS fuses -- OK
checked resistance in solenoid valve relay and return pump relay -- OK
Checked wiring from ABS unit to ABS controller --OK
Have good communication with ABS ECU.
ABS wheel sensor signals all registers fine while driving with VAG.
Reconnected ABS ECU under the rear seat.

Scanned using VAG shows ABS solenoid valve relay as 0, should be 1. I do hear a click on the solenoid valve relay when scanning ABS errors.

***Replace the ABS Modulation Unit thinking was the solenoids were faulty. Still same error code. Now waiting for ECU. This is very anoying as I really only need the auto diferential Lock to work whick works with ABS system. I live in an area where snow plow comes once aday.