Brake Pad Warning Refuses To Reset

[DRK1]

I thought I would post my experience with this issue since I see a lot of questions about it. My 2008 M3 Coupe brake pad warning light came on as a result of the service indicator counting down to zero. It said all pads had to be replaced (based on mileage, not actual wear of the pad sensors which were tied off due to frequent pad swaps for the track). I double checked all 3 pad sensors, and they were intact. I tried the reset procedure using the odo button and the BC button on the turn signal stalk, but it refused to reset. I also tried using my AutoEnginuity ODB tool and it refused to reset.

Only after changing 3 apparently good pad wear sensors to new ones did the warning reset sucessfully using the odo button/BC button. I then checked to see if the old brake wear sensors had self-destructed, and all indicated a short on a low resistance ohmmeter (i.e. they were ok). This leads me to conclude that the car's computer system looks for the brake wear sensors to be disconnected and then re-connected to determine if they have been replaced. If it thinks they are not replaced, it continues to issue a warning.

Strangely, none of the service people (including manager) at my dealership were aware of this. If my assessment is true, it means BMW is using a sneaky trick to force us to buy overpriced wear sensors even if the old ones are good.

I hope someone in a similar situation can try simply disconnecting all of their old / intact pad wear sensors and reconnecting them to see if this in fact will allow the brake service light to be reset. If this is confirmed, it should be posted as a sticky and the word spread widely so we can counteract this unethical sales practice of BMW!

[RickyBobby]

I've also found the sensors to be very temperamental. When I wasn't able to reset my light, I performed the old wire splice trick on my rear sensor to ensure the circuit was complete (I suspected my rear sensor was the culprit because I forgot to unplug it before a track day and got it nice and toasty )
At any rate that allowed me to reset both front and rear brake warnings.

Your theory of needing to unplug the sensors makes sense. In my case unplugging only the rear was enough to reset both front and rear.

[WillC310]

Interesting find. I can't say as I'm too surprised though. Dealer techs probably replace a set of parts defined by BMW when doing a brake job, and I bet that includes the sensors regardless if you need it or not.

[Gearhead999s]

Hmmm.That does not suprise me as I have had the same issues in trying to reset the CBS pad warnings.Good find Thanks.

[JCtx]

Man, that sucks. But I'm sure disconnecting and reconnecting a good sensor should do the trick; no way the computer is going to know the difference.

Or how about resetting the service BEFORE the warning ?

[DRK1]

Originally Posted by elp_jc

Man, that sucks. But I'm sure disconnecting and reconnecting a good sensor should do the trick; no way the computer is going to know the difference.

Or how about resetting the service BEFORE the warning ?

Yes definitely reset them BEFORE the warning comes on!
If only I had known that at the time.

[MaxL]

My rear pad wear indicator just came on too. Pads are practically new, as I was using track pads most of the summer and only swapped stock pads for the winter and drove the car less than 500 km after that. So the warning is likely mileage-based. I'm too lazy to take off wheels and brakes, especially in this cold, so I'd really appreciate any advice on how I can reset this without having to do so. I have tried standard reset via stock, but it did not work. I am not 100% sure I have done it right, though.

Thanks
Max

[DRK1]

If the indicator is mileage-based, you need to disconnect and reconnect the pad wear sensor to see if that will fool the computer into thinking you have replaced the sensor. For the rear one, it is a pain. You need to remove the wheel and also the wheel-well plastic liner to get at the connector. Not hard, just a pain. The fronts are much easier - no need to remove the wheel, just jack the car and turn the steering all the way to the right or left. That should give you enough room to reach the connector. Let us all know what happens, so we have confirmation if this works. Then we have grouds to officially blast BMW for this scam.

[2000gsr]

Originally Posted by DRK1

Yes definitely reset them BEFORE the warning comes on!
If only I had known that at the time.

I tried before the warning came on and it didn't reset, i will try disconnecting the sensor and pluging it back it and see if that does the trick. I'm not sure the sensor just counts down by mileage because i had 1600km left for a front pad change and around 8000km on the rears right before i went on a track day. After spending around 4 hours on the track racking up around 150kms. The front brake sensor indicated that i had only 200km left and 7000 left on the rears? So i think there may be other factors taken into account to determine brake pad life.

[krayzie]

Any followup to this?
I just did a rear pad change with 2000km left on the old set and tried a reset but it's not working.
Tried unplugging and replugging in but doesn't seem to work?

[Transfer]

Next track day (6/29) when I swap my wheels, I'll try this. That yellow BRAKE indicator on my dash is getting old and there is no way I want to shell out to buy new sensors when they just get zip tied back anyway.

[M3ANMACHINE]

I'm going through a similar issue. I've "tripped" my front ones using the track pad DIY, but haven't had time to do the rear yet. Hopefully it solves the issue.

[edwinm3]

What you guys need to do in this case is, disconnect the sensor and jump the two wires on the harness connector that the sensor connects to. While having this jumped, reset your light and when done, reconnect the sensor. Done it a million times and works every time unless sensor is bad.

[spool twice]

Agreed with edwinm3

[yandy]

this is why I just zip tie my sensors off of the pads. they don't really do much for me in this case, but if you depend on them, they are a bitch once you get that warning.

[Z K]

Can anyone confirm that the pad mileage doesn't reset if you plug and re-plug the same sensor (which isn't worn down yet). The only solution is new sensors or crossing the brake sensor wires?

[GewoW]

Originally Posted by edwinm3

What you guys need to do in this case is, disconnect the sensor and jump the two wires on the harness connector that the sensor connects to. While having this jumped, reset your light and when done, reconnect the sensor. Done it a million times and works every time unless sensor is bad.

im a bit useless...how do you do this?

thanks

[edwinm3]

Originally Posted by Z K

Can anyone confirm that the pad mileage doesn't reset if you plug and re-plug the same sensor (which isn't worn down yet). The only solution is new sensors or crossing the brake sensor wires?

When you reset mileage will show as if the sensors were new. it will reset the miles

[blazgus]

Originally Posted by Z K

Can anyone confirm that the pad mileage doesn't reset if you plug and re-plug the same sensor (which isn't worn down yet). The only solution is new sensors or crossing the brake sensor wires?

Pad mileage won't reset, if you unplug and replug the old sensor. On all e90 and on the brake wear sensor is not "full circuit/broken circuit" anymore. Its now a resistor. If you look at a photo of a new sensor from some parts website, you will notice that the wearable part of the sensor is much thicker than the one on your "old, but good" sensor. That part starts wearing off early on with pads, way before it triggers the light. As it wears off, the resistance of the sensor changes, and that's how the computer knows how many miles approx. are left on the pads. That's also how it knows that the sensor is old, when you try to reset with the old sensor. It won't reset, unless the sensor is new, with the original resistance. The system requires that wear monitoring to be renewed completely, only then it will allow the reset. Crossing the sensor wires would not help either. That certain electrical resistance of the new sensor is what the computer is looking for.

[spencers]

Originally Posted by edwinm3

What you guys need to do in this case is, disconnect the sensor and jump the two wires on the harness connector that the sensor connects to. While having this jumped, reset your light and when done, reconnect the sensor. Done it a million times and works every time unless sensor is bad.

Old thread, but I just tried it. Worked wonderfully! THANK YOU!!!

[gimmethemuumuu]

On my wife's E91 328i, the front brakes were replaced a while ago and the rears were coming due. However, they still had about 7-8K left, IIRC. then, all of a sudden, with no brake being done, I got the red car on a lift. I tried several resets. However, both front and rear were showing dashes and refused to reset.

The solution for me was to plug in, temporarily, new front and rear sensors. I didn't put them in the pads. I just unplugged the old and plugged in the new. Then I was able to perform the reset without issue. In fact, having the fronts reset to a full interval left and the rears now show 12K left (which seems about right looking at them). After the successful reset, I unplugged the new sensors and re-plugged in the old. Two days later and no problems. I'll update if that changes but I think we're good

An update to the general reset procedure: All I did was press and hold the tripometer reset button. After a few seconds, the yellow triangle will show. Then, after another second or two, the service info items will be shown and can be cycled through and reset. This procedure can be done any time with the key on, even with the car running. You can even get do it when the car is at a stoplight, just not while moving--just like the normal service info screen when not in reset mode.

[Vacek]

Originally Posted by edwinm3

What you guys need to do in this case is, disconnect the sensor and jump the two wires on the harness connector that the sensor connects to. While having this jumped, reset your light and when done, reconnect the sensor. Done it a million times and works every time unless sensor is bad.

Did this today and it worked like a charm !!

I took a wild guess and removed the rear passenger wheel, and jumped that sensor. I reset everything while only this one was jumped, and the red brake light reset nicely, along with the mileage for next service.

Plugged it back in, and all is great now.