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ABS light, brake light and TCS offline on 528i... ideas?

26K views 7 replies 7 participants last post by  Xero Phane 
#1 ·
I have a 2000 bmw 528i. The ABS light, brake light and traction control light are on. There are 2 stored codes on the vehicle. #105 - brake pedal switch signal and #115 - pressure sensor signal interference. Neither of the repair information systems at the garage have fault diagnosis for these fault codes. Any ideas what may be wrong?
 
#5 ·
105 is a given-check switch and cabling.

115-before you go changing parts...
1)check brake fluid levels; and make sure ABS is bled and properly purged.
2)signal interference can also be caused by dirty or failng brake sensors.

traction control takes it's inputs from the same sensors so i suggest you start there.

* sensors, modules, brain/s... these are electronic systems and just like your PC are prone to glitches. (i.e. a static charge at the sensor level or a surge in the module is enough to trigger the "check lights") If your mech or tech is a friendly 1 and looks after ur interest, the proper way to do this, is to clear the light at least a couple times... lucky you if it goes away. if it doesn't, then that is the time u take corrective measures :)
 
#6 ·
Hi guys, my e39 has the traction control light also the abs light on. the cruise control also was not working but i had a fiddle with the rear speed sensors and the lights are still on but the traction control light now comes on. it didnt do that before. so im thinking maybe the system just needs resetting???? what do you think? any ideas?
 
#7 ·
First off, thank you for everyone who has contributed in years past. It's all been really helpful!

Second, sorry for resurrecting a 10-year-old thread.

I'm curious what the OP ultimately ended up with. I have a 2003 E53 (X5) 4.4 that has had the three amber lights come on intermittently. It's been happening for awhile, and while I feel very close to a solution, it's still somewhat a mystery. A couple of notes before the specific ABS/DSC/Brake issue: My power steering reservoir and coolant reservoir have both had leaks right onto the main connector. I've recently dried and cleaned the connector, as well as applied dielectric grease into each hole. Also it sounds like my U joint or something in the neighborhood is wearing out. At times, when the 3 lights come on, it will cause the rear brakes to completely lock up. It doesn't put the vehicle to a screeching halt but instead creates a pretty severe brake drag to the point the rotors heat up red. I've just replaced those rear rotors, brake pads and both brake wear sensors.

As for this issue, INPA is consistently indicating the same errors as the OP. Here's the interesting part (for me at least): when watching the live data, both the pressure sensor and the brake switch lights fluctuate constantly until I press the pedal. Then they seem to act normally from what I've seen so far. Does this mean the brake light switch may be the culprit... or something else? Here's what I'm down to (I believe):
* bad brake light switch
* dirty/bad speed sensor(s)
* bad ABS control module
* bad DSC pressure sensor


Thank you!
 
#8 ·
UPDATE:

I found the values do fluctuate when pressing the brake pedal. I took 3 videos of the live view analog behavior in INPA but I can't post links yet. PM me if you'd like to see. In summary, initially the pressure spiked briefly to >200, the lights came on and the pressure quickly subsided. Without pressing the pedal the pressure and the brake light switch values would fluctuate around 1 unit each (+/-1 for pressure, +/-0.1 for brake light switch). When pressing the pedal, the values would raise as normal, except the brake light switch was "!12.1" and the pressure would fluctuate around 48. Without pressure again a few seconds later, the pressure spiked to 291 and held that value for about a minute, after which it went back to its "normal" ~48 range.

So now the suspects are:
* master cylinder
* brake light switch
* speed sensors
* ABS control module
* DSC pressure sensor
 
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