850 ABS TRACS OFF

this might help:

A VERY common failure on 850s! Your ABS controller has almost surely failed. Replacements from Volvo are around $500. You can read a little more about it at:

Lots of folks have reported good results from having this guy repair their units:

John

I had the Identical problem with my 97 850 don't ask why but I removed all excess keys and fobs from my ignition keyring just kept the remote locking fob and one house key plus ignition key. I have now had no abs or tracks lights showing for 3 months. In fact everything is fine. Hope this may help, it was definately cheaper for me than buying a new module! John Kelway

There's another problem that turns the ABS and TRACS OFF lights on that involves the ignition switch, this sounds like your problem. Usually it's accompanied by a couple of other things (power mirrors, turn signals, rear defogger) not working if the problem is with the ignition switch. In your case, I'd change my ignition switch:

Hello Mike What makes you think the problem is in the ignition switch rather then control module or a sensor? Thanks...Al

In your case, I think it's the control unit. In John Kelway's case, I think the problem was caused by the ignition switch. If your signal lights work when the ABS/TRACS OFF lights are on, then the cause is not the ignition switch.

Thanks. I note what you say about the signal lights, but as the ABS/TRACS lights have not come on since I removed my excess keys I am loath to tempt faith! John Kelway

Replacing the ignition switch is very easy and the part is not expensive. I think it cost me something like $50 from the dealer and it took me no more than an hour to replace. Taking the extra keys and fobs off your key ring is a good idea since I believe the extra weight is part of the problem.

Gus