Fun with ABS Module and the wonderful trifecta of dash lights

[scottbayarea]

Well I finally got off work travel and a 2600 mile motorcycle ride through the smoky mountains (it was awesome) so I could investigate further my quest to clear the wonderful trifecta of ABS lights. I had installed a rebuilt ABS module and coded it but the lights didn't clear and I had to go on the motorcycle ride so today I started digging.

With the new module, I was getting front left and back right wheel speed sensor faults. I don't believe in coincidences of multiple failures but just to be sure I replaced the front speed sensor and it did not clear. That leads me back to the module. I put the old module back in and monitored the speed sensors while I drove it down the driveway and the speed sensors are fine.

With the old module I am getting the brake pressure line fault. Research seems to indicate that this is pretty much a bad module and not the sensor. It is reading a constant 170mbar (around there) and does not vary with brake pressure.

So I wonder if I really programmed the module correctly. I used SSS/Progman and it sure looked and acted like the programming took. I wonder if there is a way to tell that the module is programmed correctly.

I sent a message to the module rebuilder and throwing it out to the many experts around here. Any tips or advice would be much appreciated

[jclausen]

I had pressure faults and just replace the sensor, all is good. My dsc module had been replace by the previous owner

[1823alex]

I had a brake pressure sensor fault & previous owner's mechanic replaced the brake pressure sensor and still had the fault so I got a rebuilt module from my parts guy for $80 & it fixed all my problems. When you put a new module in your ABS & BRAKE light should go away but your traction control light will stay on until it is coded to the car.

[scottbayarea]

Thanks for the replies. I have the pressure sensor on order. And that is really good info about the lights. All three lights stayed on after installing the rebuilt module. I am leaning towards a bid module. The vendor has reached out so we will see

[IanCampbell]

Hi,

I had a long saga of ABS, ASC and brake warning lights coming on in varying combinations on my E46. Garages had diagnosed different wheel speed sensors as faulty and they were replaced. This included an apparently faulty rear left hand sensor but I discovered later that it also drove the speedometer and that had worked so the sensor wasn't actually faulty. Each time sensors were replaced everything was fine for a while.

Wiring was checked OK end to end. I bought a fault code reader and diagnosed (apparently) 2 faulty sensors. I eventually replaced all four with 3rd party sensors.

Failures continued intermittently and the conclusion was that, since everything else was OK it must be the ABS unit. This was sent to a repairer who claimed to have repaired (??) faults. Re-installed, all was OK for a while and then the intermittent faults started again.

I poked around with the code reader and found that there was an error in the auto gearbox management unit - complaining about lack of wheel speed info. I pulled the plugs on ABS and auto box control units, cleaned with aerosol contact cleaner, stuffed the female parts of the connectors with silicon grease and....... a year later no further problems.

Won't work for everyone's situation but try out a simple and cheap fix before getting too technical.

[theWalkinator]

Here are the codes pulled from my car:
6 - Wheel speed sensor front right inplausible signal
69 - Brake light switch plausibility
73 - Pressure sensor line

I have replaced wheel speed sensors on all 4 wheels, also replaced brake light switch sensor, trifecta lights are still on, it is really the pressure sensor went bad? Trifecta lights are on 99% of time, but occasionally on a hot day when I turn KTMP on to monitor coolant temperature, and then I shut off the car, restart the car, trifecta lights are off. I also lost BC functions and cruise control is not working neither. Ignition switch was replaced too. I still don't believe it is the ABS module's issue. Car is 2002 540i.