Volvo Repair: ABS light on 1993 940, wheel sensors, haynes manual

Question
The ABS light on my 1993 940 just came on.  My Haynes manual does not have any instructions on trying to troubleshoot this problem.  Any suggestions?

Thanks,
Henry

Answer
Henry, Haynes is good for one thing.  Toilet paper.  2 things that can be an issue on those.  The relays are 1.  I have seen those fail.  They are located under the cover of the ABB pump.  The second thing is the front wheel sensors.  You can take them out and clean them first with carb clean and 9 times out of 10, the light goes off.  If not, then one of the relays is the culprit.  I hope this helped you.  Roger