fixing ABS light

[swerling]

I figured if the car thought it was in motion, since I had the engine running, and it detected the rear wheel sensors but not the front then maybe the front sensors are bad? The light did not go on when I manually spun the front wheels as well independently. Each time I spun a wheel only that wheel was off the ground.

[swerling]

I started the vehicle. With it running I jacked up each wheel and spun them independently while the others were grounded. Only the rear wheels spinning triggered the ABS lite. I know the ABS system doesnt activate until the speed of the vehicle is above 6 MPH or so. I also thought that if the computer picks up a signal from the rear but not the front that maybe the front sensor/s could be bad. I also thought that if the front wheels are spun but the sensors are defective and the rear wheels are not spinning to send a signal then the computer has nothing to compare therefore it doesnt know the vehicle is moving and doesnt activate the ABS lite.???!!!

[DRW1000]

Ingenious bit of troubleshooting there. The only comment I can make is that the car PCM knows whenever the car is moving. I am not sure but it is conceiveable to assume that this information can be (or is) shared to the ABS computer too.

I too have ABS light illuminated. I have checked my fluid and had a good look at my front sensors. I am convinced that my back ones are simply dirty. There is a lot of brake dust in the drums and the backs are known to get dirty and stop working. a simple cleaning of the sensor often corrects the problem. (so I am told). I had trouble removing my drums and I need to back off the shoes in order to remove them but I am wondering if the ABS sensor can be removed with the drums still attached through the backing plate? I have a 99. If so I may simply drive up on ramps and try the cleaning.

[12Ounce]

DRW
Yes.

[swerling]

In this test I had the vehicle running. I also know the ABS system doesnt "kick in" until the vehicle senses it at or around 7MPH. I thought if the front wheels were spun and no lite came on then the front sensors were not detected. Likewise when the rear wheels were spun the vehicle must have sensed that those sensors were working but couldnt get a read from the front sensors therefore setting off the ABS warning lite.??!!

[swerling]

Just did the rear brakes yesterday , cleaned everything, ABS lite still there. removed and cleaned both front sensors as well. No luck