ABS system is possessed

[Benjamin '97 WS6]

Like I said, my ABS requires an exorcist. The demon came about after I had my car up on jack stand to replace some exhaust hangers. Stay with me I'm going to try and describe what she is doing. When I first turn on the car it lights up ABS Inop and does not turn off like normal (which I know this is a common problem, but this is the first I've seen of it). Next, when the parking brake is engaged (while the foot pedal is not engaged) and the car is at a standstill, the Low Traction light turns on and starts to flash at a constant rate. I can hear the solenoid clicking from under the hood and it coincides with the flashing. At this point (with the parking brake still engaged) I can press the foot brake and the previously flashing Low Traction light is now solid. If I hold the foot brake for 5 seconds (or so) the ABS Inop light and the Low Traction light turn off and everything looks normal. That is until I disengage the parking brake or take my foot off the brake and then the ABS Inop light turns back on, but not the Low Traction. I can re-engage the parking break and I’ll see the same series of events all over again. I haven’t driven my car since this started so I don’t know if any strange things would happen while I was moving. This problem started after I replaced some exhaust hangers near the transmission and the axel. Does anybody have any ideas? My only thought was that I could have bumped the rear wheels ABS sensor. Does anybody know where that is located (non-traction controlled so I will only have one)? Any help is greatly appreciated.

[Joe 1320]

The nontraction control cars have 3 abs sensors, one at each front wheel hub and one on top of the differential housing. If your brake test took place with the wheels off the ground, the amount of brake force required to keep the wheels from moving will often illuminate the low traction light, often the brake force in that kind of test doesn't jive with the factory parameters programmed into the control module. Before you do anything, I would located the rear abs sensor on top of the differential housing, disconnect the harness connection and clean thoroughly with electrical contact cleaner. Reconnect the harness, put the car on the ground and perform your brake test. If you still have a problem, let us know.

[Jeff_in_Atl]

Like Joe said if you did this test on jack stands that is the problem. If the rear end turns and the front doesn't it will trigger the ABS light. Every time I go and get my emissions done they put it on the roller thing to load the engine. It triggers the ABS inop light. They take it off the rollers and I have to turn the car off to reset the light then all is fine.

[Benjamin '97 WS6]

I had already put the car on the ground before I started her and noticed the problems. So there wouldn’t be an issue with the wheels being in motion, the car was definitely stopped. Today, I took the sensor out, inspected it for damage, cleaned out the connector, reinstalled it, but there was no change. I noticed the sensor had a few very small scratches in the plastic near the magnet (the end that inserts into the differential). I figure my next step is to replace that sensor. Any thoughts? Thank you for the help.

[Injuneer]

What happens when you actually drive it? Rather than worrying about what it does on jack stands, or what it does when you return it to the ground without actually driving it?

[Benjamin '97 WS6]

Ok, the ice in Dallas has cleared and I was able to drive to car for the first time today. When I’m driving all that happens is the ABS Inop light stays on. Just to clear the air, of this was done on jack stands. I’m not really concerned with what it would do on the jacks. But I am concerned with the strange things my computer is doing when I put the parking break on and why my ABS doesn’t work.

[Injuneer]

You can get the EBCM module scanned with a high end scanner, like a Tech-2, and it will tell you exactly why the ABS doesn't work. If the "ABS INOP" light is on, it may be because the 3rd brakelight in the back is burned out. Could be one of the three sensors is faulty. If the problem showed up AFTER it was on jackstands, I'd check the wiring harness for the front sensors, and try blowing the dust out of the front bearing cartridge, where the sensor is located.