Dreaded ABS+Brake+DSC issue
 

I'm in dire need of some assistance. Several weeks ago the 3 lights came on and since have not extinguished on my '01 4.4. The peake code reads 78 (Vehicle Speed). So after a bit of research I came to the conclusion that it had to be one of the front ABS sensors because both speedo and cruise control works without issue. So I ordered one and installed on both front left and right but lights will not go out. I cleared the codes and drove at least 5 miles but no luck; code 78 reappears. What are the chances that one of the rear ABS sensors is bad? Is there anything else I can try to fix this problem?
Any info would be greatly appreciated.
Thanks.

The code reader should tell you which sensor you are having issues with, otherwise you have a 1 in 4 chance of guessing right... And once you know for sure which wheel speed sensor the fault is for you can simply swap that sensor with the other side to see if the fault stays in the same place or follows the sensor.

Thanks for the info Weasel. My peake reader just give the error "vehicle speed", nothing more. I also had a friend hook his reader up and it read "Speed Sensor A". The question is which sensor is "A"? I assumed it was one of the front sensors but so far no luck.
By chance do you have any idea which sensor this may be?
Thanks.

No, couldn't tell you from that little info. I have the luxury of the GT1 at work, and that gives you every detail including at what mileage and speed the faults were set at, etc. Also with the GT1 you can actively read the wheel speed sensors... alowing you to see the sensor that isn't reading, swap it from side to side and see if the problem follows the sensor or stays at the same corner. If it stays I can look up the wiring schematics in it and check the wiring. If that is good, I make the deduction of the failed module/component from the location of the failed sensor circuit.

That GT1 sure sounds like the tool to have. I guess it's off to the shop for further diagnosis.
Thanks for the help Weasel. :thumbup:

It appears to be the ABS controller. I've rebuilt mine and other bimmers for the very same reason. Where are you located? There might be a GT1 owner in your neighbor. Good luck!

Left rear fault can be the instrument cluster, right rear fault can be the DSC module... just gotta know which wheel the fault is for before any further diagnosis can be done.