Antilock problems after service

[clfitz@inetone.net]

Hello, all...

Once again I turn to the Q-list for some answers.

I recently had my 88 Q90 in for a wheel bearing and cv-shaft 
change, and when I got it back, the anti-lock brake light stays on.  
Anti-lock is *not* functioning, either, as I discovered after a test (on 
an empty side road, of course.)   ;)

As I was out of town, the service wasn't done by an Audi dealer.

I'm thinking that the mechanic somehow messed up the antilock 
sensor; any other ideas?

As always, any ideas, help, etc., gratefully acknowledged and 
appreciated immensely!

Carlyle