Brake Sensors

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01-08-2010, 05:50 PM

#11

Rudy

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Quote:

Originally Posted by njlou' post='1086975' date='Jan 8 2010, 09:18 PM

Is it possible that this driving information is also stored on your "key"??

The key stores the current CBS service interval -- I don't think it stores any particular data on how you drive, etc.

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01-08-2010, 06:27 PM

#12

twh

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Quote:

Originally Posted by PraiseTheLowered' post='1084600' date='Jan 5 2010, 03:11 PM

great question, i ran into the same thing with mine when I bought it it had 24k left on the front and rear so i bought the service warranty because i knew I could actually use it for that. After a year of driving now the front is 50k and rears is 40k.

AFAIK the sensors are just tiny fiber optic lights that measure the pad depth so there is a constant output on them, so why it would be low and then increase over time is far beyond me and even all of my SA's couldnt answer why it did this. Just check the pads and you should be good to go.

The brake pad sensor is not fiber optic. The idea is that if the bake pad wears down to the end of it's life, the brake sensor will wear off some plastic on the sensor and make contact with the brake rotor. That completes a circuit and lights up the "replace me" light. While I haven't inspected a BMW sensor beyond looking at a couple pictures, this is how my Benz did it. I don't think the brake pad sensor has any role in estimating pad life - all it does is tell you "we're done". The estimating is done by other things, like driving style, highway miles, etc. A Toyota and Nissan I had used a "noise" sensor. It was a little metal clip on the end of the brake pad that would make contact with the rotor and make an awful noise. They figure that's enough for someone to get concerned and take the car in.