Abs/asc Light On - Please Help!!!!!!

[Avatar1]

Hello guys, I really need help as I am at the end of the rope with my vehicle:

I have a 2000 523ise (525 engine) manual 5 speed.

The car is equipped with ABS and ASC. A few months back the ASC/ABS light went on, and when I put it on the scanner it said Rear Left Speed Sensor.

So naturally I changed the sensor and shortly after the light came back on...

Back on the scanner - Left Rear Speed Sensor Circuit......and the speedo does not work; So:

1. Cleaned the sensor's ring
2. Checked wiring visually
3. Checked that all tires are made by the same manufacturer and have similar thread thickness

So I went into troubleshooting mode....abserving the car carefully and this is what happens:

1. When you start the car in the morning - the light is off - speedo works....upon driving it a little distance (about 15 minutes or so) the light will come on.

2. If you start the car and just leave it running the light will come on without moving the car after a little while 15-30 min or so.

3. If you unplug the wire plug from the ABS pump/modulator - and then put it back on the light will dissapear and the car will run normally for an amount of time (again about 15 min or so) before coming back on.

4. I removed the modulator off the pump (6 screws) and cleaned the inside out with aircraft electronics cleaner(**great stuff) - replaced the modulator on the pump - and the light stayed off for what looked like about 15-30 mins or so.

I dont know what to do much more than that. Can someone PLEASE help me, I need to fix the car ASAP for a driving test - which cant be taken without the speedo working. Any ideeas would be appreciated. Thanks.

[Avatar1]

I have diagnosed the problem.

HERE'S HOW TO SEE IF IT'S THE ABS CONTROLLER UNDER THE HOOD OF THE CAR:

1. GOTO AN OFFICE SUPERSTORE AND BUY A CAN OF COMPRESSED AIR
2. RUN THE CAR UNTIL THE LIGHT COMES ON
3. USE THE SPRAY UPSIDE DOWN AND SPRAY LIQUID OXYGEN ON THE UNIT UNTIL IT IS COLD (COLD COLD NOT EVEN ROOM TEMPERATURE)
4. IF THE LIGHT GOES OUT - ITS THE ABS CONTROLLER

THANKS EVERYONE!