Rear Brake Light - Mileage Countdown

[sometorque]

Greetings:

I just purchased a new to me 2011 135i DCT. Really loving my time with the car and often find myself wanting to drive it around "just because". I've recently begun noticing that the following light pops up for a few seconds when I start the car, which I've concluded is related to the rear brakes. Front and rear brake rotors and pads were replaced by the dealer just before I purchased the car, and the pads have plenty of life left on them.



I tried the reset method, per the "DIY reset lights" thread on here, but after holding reset and watching the clock spin, the mileage remains at 1300. How would I reset this completely to reflect there being new pads installed? Thanks for the help and really excited to be on this forum

-Steven

[sometorque]

Bump?

Did a little reading. From what I'm gathering, I may need to replace the rear brake sensor for it to allow me to reset. Anyone know if this is the case? Front brake service indicator reset just fine, but anytime I try the rear, the clock on the dash spins but simply stays at "1300 mls".

[pj.rodriguez]

You need to have the sensor "trip" and then you can reset it with a new cable. Alternatively you can short the system using a thin wire and plugging it in directly to where the sensor plugs into the harness, reset it, then put the sensor back onto the car. Are your pads due to be changed soon?

[sometorque]

Originally Posted by pj.rodriguez

You need to have the sensor "trip" and then you can reset it with a new cable. Alternatively you can short the system using a thin wire and plugging it in directly to where the sensor plugs into the harness, reset it, then put the sensor back onto the car. Are your pads due to be changed soon?

Pads are brand new. Dealership changed them when they put the car up for sale, so they may have about 500 or so miles. I'm assuming that they simply either never replaced the sensor/reset the service light after doing the work. So I can simply unplug the sensor, short the two wires, jump in the car and reset the light using the ODO/BC method? Seems simple enough, Thanks for the help!

On a side note, the mileage counter hasnt budged from "1300 mls" due in the last 250 miles or so. Anyone ever experience that?

[pj.rodriguez]

Ohhhh. Okay. They just didn't change the sensor. When it actually starts wearing, then the value will change. If it was me, I would just leave it because it will not change until the sensor actually starts wearing. On your next pad change, when the sensor trips, then you will be able to reset it.

[_Ryan_]

Two options in my opinion:
- Take it back to the dealer
- Ignore it


I ignore mine

[Kgolf31]

Originally Posted by sometorque

Pads are brand new. Dealership changed them when they put the car up for sale, so they may have about 500 or so miles. I'm assuming that they simply either never replaced the sensor/reset the service light after doing the work. So I can simply unplug the sensor, short the two wires, jump in the car and reset the light using the ODO/BC method? Seems simple enough, Thanks for the help!

On a side note, the mileage counter hasnt budged from "1300 mls" due in the last 250 miles or so. Anyone ever experience that?

Originally Posted by pj.rodriguez

Ohhhh. Okay. They just didn't change the sensor. When it actually starts wearing, then the value will change. If it was me, I would just leave it because it will not change until the sensor actually starts wearing. On your next pad change, when the sensor trips, then you will be able to reset it.

I'd have them change the sensor.

The brake wear counter is odd. It counts down with miles and relies off the sensor for it as a safety factor.

Without the sensor changed out, the mileage will still count down and trip the light. The mileage counter also varies the "miles left" depending on driving style.

[sometorque]

Originally Posted by Kgolf31

I'd have them change the sensor.

The brake wear counter is odd. It counts down with miles and relies off the sensor for it as a safety factor.

Without the sensor changed out, the mileage will still count down and trip the light. The mileage counter also varies the "miles left" depending on driving style.

Yep. After about 300 mostly highway miles, it dropped down to 1200 miles to service. I found the sensor at a local auto parts shop for $12. I'm assuming it's as simple as replacing the sensor and resetting the light correct? If so, I'm just going to buy the sensor, swap it myself this weekend and save a trip to the dealer.

[Kgolf31]

Originally Posted by sometorque

Yep. After about 300 mostly highway miles, it dropped down to 1200 miles to service. I found the sensor at a local auto parts shop for $12. I'm assuming it's as simple as replacing the sensor and resetting the light correct? If so, I'm just going to buy the sensor, swap it myself this weekend and save a trip to the dealer.

Correct.

When you reset the light, the computer looks at the actual resistance value of the sensor to determine theoretical mileage left.

Unlike older sensors where when you trip them and break that contact, the light comes on. These...as you wear them down the resistance through the wire changes and it correlates to brake wear.

[sometorque]

Originally Posted by Kgolf31

Correct.

When you reset the light, the computer looks at the actual resistance value of the sensor to determine theoretical mileage left.

Unlike older sensors where when you trip them and break that contact, the light comes on. These...as you wear them down the resistance through the wire changes and it correlates to brake wear.

Got it. Thanks for the help everyone!

Unrelated, this has been the most fun I've had behind the wheel since I owned my s2000 years back. The 135 is a special car

[02rsxpilot]

For clarification sake, because my front sensor is pretty badly damaged from frequent track/street pad changing, if you disconnect the sensor and just zip tie it up out of the way, do you get a warning light?

[sometorque]

Bump. I have the rear sensor in my shopping cart on ECS to finally take care of this. However, I read somewhere that you have to replace both the front and rear sensors to reset the brake service indicator. Any truth to this, or can I just buy the rear sensor alone?

Thanks guys