Deep dive - can't reset break wear sensors

[tgrandahl]

Hi All,

I've put >30kMi on my E89 now so I've gone through front and rear pads.

In both cases i replaced the pads before the CBS indicators reached the "red" state.

My front required replacement first, then my rear almost a year after that. Both times i used a new genuine BMW wear sensor, and tried the just about every variant on the reset procedure found on the internet. The reset procedure didn't work for the fronts and i had seen a few threads that suggested you need to do the front AND the rear sensors for it to reset. So i waited until the rear needed to be replaced and tried again with no success. So now my CBS just thinks my front and rear are wayyy overdue.

I can and have been living with the light and warning on, but i'm concerned about resale value and that something else is broken.

I've checked the resistance of the wear sensors, they measure as a short circuit on both. I also have no problem resetting other CBS intervals like the oil change and brake fluid.

I'm thinking that something else must be wrong with my car that's preventing me from doing this.

A few thoughts / questions i'd like to run by you guys:
-What ECU reads these sensors? The documentation I've seen suggests the ABS module but it's a bit fuzzy.

-Is there a dealer diagnostic tool that can directly read the state of the wear sensors? I'd like to be able to verify that the car knows the wear sensors are in the un-worn state.

-Has anyone experienced custom coding blocking brake resets? I had some coding changes made on the car to attempt supporting LCI head lights that i swapped to. I also made some changes to the coding of the KOMBI, however nothing related to CBS. I also tried rolling back the coding of my KOMBI to my stock backup, still cant reset...

I know this is a common issue to be discussed, but I feel I've exhausted the typical solutions that are discussed.

Worst case, is there a way to code the brake wear CBS to be disabled? I'd really rather not do this but if it were between this and a few thousand dollars to a dealer i'd rather disable it.

[Tangent]

I'm currently in the same boat. I replaced front and rear pads and both wear sensors yet the system refuses to let me reset them. My next step is to operate on the old sensors and short them out and see if it lets me reset with those plugged in.

[bigendbob]

I had same problem, I let mine go to -400 miles, just go to a independent garage and they will reset using a common tool.
I gave up after a few weeks using all sorts of weird and wonderful methods, to no avail.

Once reset I just tied up out of the way the new wear sensors so has to not have the hassle again.

[tgrandahl]

That's interesting. Do you have any other modifications done to your car?

I'm really wishing there was a way to view what the relevant ECU is reading from the break sensors. This would at least help identify if the thing preventing us from resetting is a hardware or software condition.

I have INPA and DIS but i'm not experienced enough with them to know what tool is the right one and where to find the function i'm looking for. I also commonly encounter errors with INPA that make me think the software version i have is too old for my MY10 E89.

[BQTuning]

I think its the Ebrake reset you guys are running into

There is a manual procedure for E brakes if you going to dodge doing it the way the dealer does it via OBD port. Google it, I was able to replace my rears with new sensors and the light went away. You have to toggle the ebrake on and off or something like that while interacting with the dash to reset the sensors.

As for doing it via OBD port it much easier. The BMW ECS Schwaben scan toon puts the car into "workshop mode" and retracts the ebrake automatically when the car is "off the ground".

http://www.e90post.com/forums/showpo...3&postcount=50

[bigendbob]

Something like this needed;
http://www.ebay.co.uk/itm/Autel-EBS3...IAAOSwEK9T5KGL

But easier to pay a few $$ and get a independent to reset.

[Tangent]

Mine at least definitely isn't the ebrake. The iDrive is reporting that the rear pads are 7,000 miles overdue, (they hit the wear sensor) and that the front pads have about 20,000 miles left. I replaced both front and rear pads and sensors. Using the display to reset the rear pads fails, I can't even attempt the front brake reset since they aren't reporting as a service that's due, and using the Carly app to try to reset the front or the rear also fails. Once I have the time to short out and install the old sensors I'll post if it worked...

[rking117]

Originally Posted by Tangent

Mine at least definitely isn't the ebrake. The iDrive is reporting that the rear pads are 7,000 miles overdue, (they hit the wear sensor) and that the front pads have about 20,000 miles left. I replaced both front and rear pads and sensors. Using the display to reset the rear pads fails, I can't even attempt the front brake reset since they aren't reporting as a service that's due, and using the Carly app to try to reset the front or the rear also fails. Once I have the time to short out and install the old sensors I'll post if it worked...

I wish i could be of some real help here but the indicator that you are talking about is able to be reset via the ODO button and turn signal stalk on the dash. for me the trick was to have the key dongle inserted (or near the column if you have comfort drive) press the start button WITHOUT pressing the brake. this turns on the ignition. from there press and hold the ODO button until the Serviceable Indicators appear. Then using the stalk scroll through the menu until you find rear pads and press the button on the end of the stalk it will say RESET. This is like a question "RESET?" Press it again to reset the indicator. it may take a minute to complete (why i dunno it is only software) the indicator that you are getting is not sensor related it is mileage related so resetting it here will work. No tools are needed for this application.

[Tangent]

Yeah, those are the exact steps I've tried multiple times and that I've used for resetting brake fluid service. I'm able to get to the reset but within a moment of resetting it the warning chime goes off and I get the "rear brake pads at minimum" notice on the iDrive and the car on the lift display in the IP.

[bigendbob]

The stalk method won't reset once you are the minus side.
And high mileage left also won't reset.
Have been down this road.
Don't have sleepless nights, just go indy and have them reset.
I suppose it's to ensure you physically check the discs and pads and don't just reset.
I have tried every method to reset, including leaving battery disconnected over night.

[mikeinaustin]

I did the stalk method for both front and rear brake pads, worked fine for me. 2010 z4.

[rking117]

Originally Posted by Tangent

Yeah, those are the exact steps I've tried multiple times and that I've used for resetting brake fluid service. I'm able to get to the reset but within a moment of resetting it the warning chime goes off and I get the "rear brake pads at minimum" notice on the iDrive and the car on the lift display in the IP.

Ahhh that is the sensor i think. If you replaced it then it is either defective or it is not making a good connection. There is only one sensor per axle i believe the rear is the left hand wheel. SO i would recommend replacing it again. ( i am talking about the senor that is on the brake pads themselves). If that sensor breaks or loses connection that is when the indicator comes on. It cannot be reset while in an electrical "open" state.

[Tangent]

Originally Posted by rking117

Ahhh that is the sensor i think. If you replaced it then it is either defective or it is not making a good connection. There is only one sensor per axle i believe the rear is the left hand wheel. SO i would recommend replacing it again. ( i am talking about the senor that is on the brake pads themselves). If that sensor breaks or loses connection that is when the indicator comes on. It cannot be reset while in an electrical "open" state.

The sensors are left front and right rear and yeah, it wouldn't surprise me all too much if they're sketchy. It's just frustrating because of how buried the sensor is in the back. I'm gonna start with shorting out the sensor I removed and if that works I'll leave it at that. Considering how much meat was left on the pads with the sensor screaming at me already I'll just take a peek at them every once in a while instead...

[bigendbob]

Front left, rear right.
I tried shorting, doesn't work.
I tried new, doesn't work.
Tried open circuit, doesn't work.
I tried battery off/on, doesn't work.

I tried local Indy that reset it for the cost of two beers.
Sorted.