ABS Light On

[ride0238]

I have a 1992 Audi S2 that I imported from Spain last year and I'm finally getting it squared away, the ABS light is on and because I am here in the USA I am having a hard time detecting the problem, any help would be great..

[twoqu]

If its the earlier version with the ABS cancel switch you coild start by reading the post below yours in the related section! Might be something of use there.
If thats not helpful then it would be useful to know the S2 variant and what exactly the issue is. For example does the light fail to go out or does it go out and then come one when you drive?

[ride0238]

The light is continually on, it never goes off. It has the 3B motor.

[twoqu]

OK, that thread might have some useful info. Unfortunately its a matter of detective work buts its probably electrical. The ABS relay is a prime suspect so you will need to locate that first. Its quite distinctive having a red 10A fuse in the top.

[ride0238]

Does anyone have the ABS relay partner number? The relay with the red 10a fuse, please help

[twoqu]

I believe the p/n is 443927826. But look, without testing and eliminating things its pretty pointless and possibily expensive just replacing components in the hope you get lucky. For example if the relevant power and earth signals are present and neither the ABS switch or the diff lock signals are evident then it would leave the relay as suspect. Obviously the relay also has a fuse. You could also bridge the contacts temporaily thereby eliminating the relay to see if the light extinguished. You can wade through this thread for the procedure:
https://www.s2forum.com/forum/techni...0v-abs-problem

[ride0238]

Yes you are correct, I will test it to see what happens. Thanks.

[twoqu]

Check Fuse 31 in the fuse box as thats an easy task. I guess it should be labelled on the fuse box cover.
Out of curosity I have popped the cover off the ABS relay and its much more complicated then you would expect. It is essentially two circuit boards with a relay coil in the middle! Anyway, hopefully you have enough info to be making a start at diagnosing the issue. Good luck!

[piotr]

I think you should get yourself little code reader that will work with your car and check Dtc-s first before you will jump from one component to another and try guess .

[twoqu]

No ABS diagnostics on early systems including 3B's I believe. I guess if you don't have a cancel switch you have diagnostic capability.

[Error404]

The ABS system on the whole is very reliable. Most problems are caused by incorrect sensor gaps or debris on the trigger teeth. You can test the sensors with a scope. As above, if the light goes out after starting the car but comes on shortly after you start moving, it’s almost certainly a sensor issue. If it’s aleays on, check the relay board for dry solder joints. Also check the condition of the wiring and connectors - take the black cover off the ABS pump, there are simple switching relays under there too. Check the ABS ECU is present and plugged in under the rear seat.