re. 1993 S4 ABS light

[Ben Swann]

Jim,

Most likely one of the ABS sensors is flaky or  associated wiring. Remove, 
clean and reseat - careful not to press back in too far.

I have had this exact problem in most of the 200 and 5000 series cars I've 
owned - BTDT 2manyX.

Identical problem with the rock candy in the ABS off switch on my 200Q20V 
avant too, but was not the culprit.  Folks just love to spill their soft 
drinks down there.

Ben

[From: quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com] On
Behalf Of AUDIJIM at aol.com
Sent: Sunday, November 27, 2005 8:54 AM
To: s-car-list-request at audifans.com; quattro at audifans.com
Subject: 1993 S4 ABS light


I have an "Anti lock Off" light on, on my instrument cluster. The previous 
owner said it needed a rear ABS sensor. OK, no problem. So I changed them 
with known good sensors from a 1992 S4 that had zero issues. After I lifted 
the rear seat to get at the rear ABS sensor connectors, I found the ABS 
control module unplugged! So I plugged it in and took her for a drive. The 
light came on again. I went digging around in the engine bay and found both 
of the front ABS sensors unplugged. So I plugged them in and took her for 
another drive. No light until I step on the brake. And the brake feels sort 
of hard until I am almost stopped, then I feel the ABS pump go on and the 
pedal goes down a little farther and the Anti lock Off light comes on. I 
have tried to read the ABScontrol  unit with my VAG COM, but it is unable to 
read it. Is the ABS control module able to be read? Just to try it, I 
removed the cover from the ABS pump in the engine bay and swapped the two 
relays and tried it again. No change. I will
physically change the front ABS sensors and see what happens. I have two 
brand new sensors in the box if I need it, but I will try my "good spare" 
ones first. I just wish the control module could be read. I think that would 
send me in the right direction if it was getting a fault I could read. Also, 
the rear diff  lock switch was stuck. It was rock solid with spilled soft 
drink or candy of
whatever the previous owner got in there. I replaced the switch and I can 
get  the Anti lock Off light to go on and off with the switch. The rear diff 
lock  out indicator light on the center consol now works. After I drive it 
and go  through the first stop and the light comes on, if I cycle the rear 
diff switch,  the light on the instrument cluster goes off. Maybe I have a 
problem with
the  rear diff lock out indication switch at the differential?

Any thoughts?

Jim]