robgosty

Just got 98 bm 325 tds very happy man BUT,after driving 15-20 minutes abs and traction lights come on,turning ignition off and restarting sometimes cures it,other times leave car for 5-10 minutes all ok,until next time PLEASE HELP this is driving me mad

romabimmer

Speculation:

Since it's an intermittent light. I would bet on the ABS pump, valve block or lateral g sensor. For this simple reason, the wheel speed sensors and brake pressure sensor are constant sending units. Which means if they go the light SHOULD come on right away and stay on. The others are only checked during pre-programmed self-checks, so until this check is run the ECU has no way of knowing if they work.

ABS pump is the most likely. These go prematurely if the brake fluid isn't changed on a regular basis.

Also can be sensors:

Since the ABS is also on, my fist guess would be the wheel speed sensor. However it could be the lateral-g sensor or brake pressure sensor since BMW uses these to give the ABS a little more sophistication.

But those are the 3 sensors used by both the ABS and the Traction Control.


Conclusion:

Problem is that you can only test each with an ABS/TC/ESP tool that hooks up to the ABS ECU. Translation: you need to find a technician with the proper equipment and knowledge.

In the mean time try and activate the ABS and Traction Control and see what happens. Does the ABS activate or do the wheels lock up? Do the rear tires spin freely on a damp surface?

For instance, if the TC activates but ABS does not then I would bet on a front wheel speed sensor.

__________________
My Technical Website on Brake Systems

robgosty

cheers,when lights are on traction control and abs are not working eg lock wheels when braking and spin from standstill,iguess its off to bmw to get the problem solved big bucks tho:shocked:

badboy325is

i would have to believe it is wheel speed sensor. the same thing was happening to me. i would hit a bump and the lights would come on however after turning off my car they would be gone. eventually it stayed on. and i had to have the wheel speed sensor replaced your sensor may be loose and when you hit a bump it breaks the connection and sends and error to the ecu which wont clear out until the car is shut off

robgosty

cheers,thanks for replies,will be checking wheel sensors later today,will post back with results (if any) thanks to all

robgosty

thanks to all,problem sorted,duff n/s wheel sensor

Mac8008

I have this same exact problem on my mother's 94 325i. We brought it to the dealer and they cleaned the wheel sensors and canged the TB assembly and we still have the problem.

We brought it back to the dealer and they said they don't know what's causing it.

I was hoping someone could help me narrow the problem down so I could start changing things and give it a shot otherwise we have to get rid of this car.