Hi Everyone-
I'm new to this forum, so forgive me if this posting is not done right.
My wife drives a 2000 S80 with about 55K miles. I started getting the ABS and STC lights on a few months ago, and assumed it was the controller. I sent it to BBA Reman to have it reapired. I guess I should have used Victor Rocha, based on this list, but did not know of him at the time. I called BBA after getting this problem, and they assured me it was tested before it left, but that I could send it back for re-testing. They also said that the Volvo repair was one of their best, whatever that means.
I reinstalled the controller, but now the ABS, STC, and Check Engine lights are on. I get a code of 1550 with my generic code reader. I can erase the code, but then after driving, and subsequently re-starting, the code arrives again. I assume this is a wheel speed sensor? How do you know which sensor? Do you need VADIS to tell? I cleaned them all. The RR was caked in mud, but all this cleaning did no help. Where is the tone ring in the rear wheel hubs? Do I need to remove a dust cover to get to it?
Also, is this the newer type ABS where you can't just test the sensors resistance? I have read that the newer sensors are actually active components, that receive 12V power on one pin, and send a signal on the other, using the bolt as a ground.
Thanks!

Problem solved! I spent a while checking all the sensors, and wiring. I found that the RF wheel speed sensor was not receiving 12V power on the brown wire, which it needs, and thus determined the replacement controller was bad. BBA Reman sent a replacement, and all is well. If anyone needs instructions on how to test the wheel speed sensors, here you go. it's not hard. The S80 uses the newer magneto-resistive type sensors.

http://www.asashop.org/autoinc/aug2001/mech.htm

Thanks for all your suggestions.

Greetings. It's somewhat possible that you installed the wiring harness to the module incorrectly. It's a somewhat tricky (the first time) locking coupler that MUST be correctly and solidly seated before its lock can be safely secured. The lever MUST be in a position that allows ALL FOUR locking tabs to be FULLY ACCEPTED before the harness can be pushed all the way down. Only then can the lever be correctly engaged to push the connection "home" and locked. Failure to follow the proper locking procedure can possibly damage the locking mechanism (usually by breaking the plastic lock tabs) if it is incorrectly engaged.
It is my understanding that if the connection isn't locked right or if the lock is broken that it could cause the module to work improperly. When properly locked, the connection should be solid and not move AT ALL when wiggled.

I have seen it related that this has been the culprit on more than a few ABS modules after re-installation (even some done by independent shops) and this would be the first thing I'd check, beyond that, I've no other suggestions at the moment.

Thanks! I'll check that out.