wpr1198

I just went through this same thing with my rear pads on my 08 528xi. You have to replace the sensor it the computer will not let you reset the system. I tried a million different ways. Once I replaced the sensor, I was able to reset with no issue.

Allen

Great news...I reset my light without replacing the sensor. Here's what I did:

1 - with car OFF and key removed...unplug the pad wear sensor behind wheel.
2 - place jumper across terminals where sensor (male) was plugged in (female).
3 - reset pad indicator light...successful reset to 25,000 miles...remove key.
4 - remove jumper...plug sensor back in.
5 - Start car...fault light is gone.

I tried to measure the resistance of my sensor...but was unable to due to tight space, no light, etc.
I do know that a new sensor reads as a short (0 ohms...terminals jumpered out). The 1st stage of pad wear reads 470 ohms, and the last stage of wear reads as an open (>20K ohms...wire worn through).

Also, I'm not sure if the jumper was the key, or if simply unplugging the sensor...plugging it back up was it...ie...the system thinks it was changed. Not positive...but pretty sure that my sensor is 100% (reads 0 ohms). I suspect that just unplugging the sensor might be the key...because my sensor is no different than the jumper I temporarily installed to get a successful reset.

Anyway...just wanted to post a follow-up. I appreciate everyone's help and ideas.

DavidF

Leo has it right. The sensors are two stage, meaning two sets of wire loops in the sensor. The resistance does not matter as the sensors are simple circuits. When the pads wear, the rotor cuts through the sensor loops and break the circuit. One loop is closer to the surface of the sensor tan the other (hence two stage). If the wire loop in the sensor (any stage) is cut, then you will not be able to reset light. If you replace the sensor and don't reset the light, it will reset itself eventually (several key on/off cycles). The sensor is a simple open or closed circuit (resistance is not a contributing factor).

Allen

This is incorrect...resistance is a contributing factor. The document in this link shows how the sensor works.

https://wiki.bentleypublishers.com/d...W+5+Series+E60

When the sensor is new, the DSC reads 0 ohms through the outer wire loop. The 1st stage of "failure" is when the outer loop wire is cut by the rotor...the DSC then reads 470 ohms...I assume you get a yellow light saying something like "brakes are getting close to needing replacement"? The 2nd stage of "failure" is when the inner loop wire is cut by the rotor...the DSC then reads MAX ohms...you get the red light saying "replace brakes now".

BTW...after driving my car about 10 minutes this morning...then turning it OFF to get gas...then back ON...my red light returned However, this time...the "remaining miles" is 0 instead of -9000. I'm not gonna try to reset it, cause I bet it would go to -9000 if I do that. I suspect my sensor is not reading "short"...wish I could have measured it.

I guess I'm just gonna jump the circuit out until I change my brakes and get a new sensor at that time...I have about 20K miles remaining on my pads.

Allen

lol...new weirdness...so the red reset light came back ON the next day after the successful reset...indicating 0 miles till service. Well, the next day after that, the light turned yellow and the miles went to 10, next day, miles went to 20, next day 30, etc. The light is still yellow, and the miles have now counted up to 90 miles.

Anybody seen this?