ABS light on

[Max Wellhouse]

I've got a C-4 that does that occasionally and the local indie mech 
said the abs sensor at the wheel was the problem.  Not sure if it's 
your left or right, but a pothole slam sent our passenger side one 
out to lunch.  Got a used one and will follow up after it arrives and 
gets installed.  Not as cheap as the relay(new sensor from Blau is $160 each)

DM&FS

At 11:05 PM 10/22/2005, Ed Kellock wrote:
>The Antilock Off light is constantly on in my '89 200q.
>
>I found the information below at 20v.org and a new fuse lasted a 
>couple of days until I
>"tested" the ABS a few more times today.
>
>If anyone had any additional information or other BTDT, please let 
>me know.  My local
>junkyard has a couple of possible ABS relay donors.  I'll see if I 
>can obtain another
>relay there on Monday for the sake of testing.  Couldn't find one 
>online where I could
>also find a price.
>
>Thanks,
>Ed
>
>
>
>ABS Light ALWAYS ON
>(J Tomislav)
>Simple Check for it is the following
>   1.. Remove footwell cover (driver's side ... this is actually the 
> whole shelf).
>   2.. Remove ABS relay (should be middle row all the way to left 
> and it has a red fuse in
>it which is 10 amp I believe).
>   3.. Look at fuse ... is it blown? If so, then here is your 
> problem. Don't bother
>replacing fuse ... it will blow again. Replace the relay. If you 
>still don't believe me,
>go ahead and put in another fuse and I bet it too will blow. This 
>will prove the relay is
>toast.
>The relay is found on all the 1990 - 1992 audi 90's and coupes ... 
>regardless of
>drivetrain. Best way to make sure is to look at the part number on relay.
>What happens is that there is this mother-of-a-diode inside that I 
>can only assume shorts
>out over time. This diode is put there to 'absorb', if you will, any 
>counter-EMF that
>occurs from turning off the ABS pump, so that the rest of the car's 
>electronics doesn't go
>berserk.
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