To begin, my car is a '96 850 turbo wagon. When I bought it, the ABS and TRACS lights were both on. Being the home brew mechanic that I am I figured that I could tackle these issues. I began by removing the ABS controller on the bottom side of the pump and re-soldering all of the cracked joints. Lights were still on.

I then visually inspected and cleaned the castellations on the CV shafts and tested the resistance of the sensors. I did not get a look at the rear ones. The lights were still on.

Being that my car is a '96, I found some obscure references to bad wire crimps under the fuse panel causing trouble with the front wheel sensors. I removed the fuse panel, located the sensor wires and re-soldered these. Still no luck.

I read elsewhere that a failing ignition switch (electrical portion) can cause the issue. I've wiggled the key while running and had no luck. Looking at the wiring diagram for the car, I found that the Blue/Red wire from the ignition switch is the one that powers the ABS/Tracs computer and while the car was running I read ~13v on this wire. I am convinced that it is not in the ignition switch.

Looking at the problem further, I decided I would test for continuity from the ABS computer to the wheel sensors. The front ones check out fine, but I cannot get a reading for the rear. According to the wiring diagram I have, the rear wheel sensors are green/white - green/black (Right Rear) and green/red - green/yellow (Left Rear).

I know that the obvious solution is to go to the dealership and have them read the ABS codes, but at the moment I am not willing to fork over a bunch of money to them for almost no work. There are a couple of side show type places that I'm going to call tomorrow and see what they will charge.

In the mean time, any suggestions as to what else to try? I am really at a loss here.

 

I have the same issue on same year. Last weekend I spent fixing my ECC and I might try to fix the ABS/Tracs this weekend. I have re-soldered the joints and thought they might still be bad.

I made a code reader for the ECC, ECU and was hoping to make it work for the ABS and TCU but after looking at VIDA? maybe? More work.

One thing that drove me crazy is the 850 is not totally OBDII compliant in 96 and, I think, the generic readers can give you the wrong info.

Anyway I'll try to post any info I have and please do the same, you obviously know what you're doing. And thanks for the info.

 

So you are not getting any resistance from the rear sensors at all? If that is the case, and you know you have the correct wires, I would assume that the rear sensors are the issue. The only other thing that you have not checked is the brake pedal switch, but if the brake lights are working, then they should be fine.

I know this is not what you want to hear, but it may be a good idea to have the codes checked because it may be cheaper then throwing parts at the car.

 

I am unsure of the wires for the rear sensors, as the diagram I have is for a 1995 model and the abs system is slightly different. Do you know where I could find a diagram for the '96-'97 abs system?

I did just go out and test the brake pressure sensor on the MC. With no pressure the switch reads no resistance. When the brake is applied, it goes to infinite resistance. On that same note, even though the switch checks out, I think that I will be replacing it. When I unplugged it, there were a couple of drips of brake fluid that came out.

I will make some calls tomorrow morning to have the codes read. Maybe I will get lucky and someone will feel sorry for me. I think I will also jack up the car and get a peek at the colors of the wires coming from each rear wheel sensor.

 

I dug around for the rear sensor wires some more. The wire colors I quoted are correct. Both rear sensors were faulty. I've got new ones on order.