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09-26-2016, 05:31 PM | #1 |
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Service Interval for front brake pads drops insane amount, resetting a problem
I have been tracking my 135i for 6 years and the last two years I see my service interval drop about 2,000 miles every 30 minute session on the track, regardless if it is Road America (heavy braking zones) or Putnam (1 or 2 heavy braking zones). Once it hits zero, I get the dreaded car on a lift symbol and brake light on the dashboard (happened only once three years ago and got it reset under warranty). When I reset on the dashboard when it reads around 2,000 miles, it only goes up about 6,000 or so miles (good for one more track day) and after two or three times it won't reset at all. Went to a dealer 4 months ago, paid a ridiculous amount for them to "fix" this, went to the track and had to come back when it wasn't, and now, 2 months later (did not track the car in July and August), my brakes went down 14,000 miles at my last event this weekend! (Left the dealer with 14,000 mile service interval which actually grew to 20,000 over the two months of no track driving). I am currently sitting at 6,000 mile front brake interval (my rears only went down 2,000 miles over a three day track period). Please note that I have both brake sensors tied off permanently. I DIY my brakes between track, auto-x and daily driving.
Has anyone experienced this? If yes, what do you do to reset the service interval to a high enough amount (20,000+ miles) so you can track the car again? I love tracking my car but this experience is making me seriously consider buying an older dedicated track car that I have no where to store nor can I tow to the track (city living, first world problems). I have seen many posts for resetting the light, but no where can I find setting the distance (miles) to get a higher amount. The community's assistance is greatly appreciated. |
10-18-2016, 02:52 PM | #3 |
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Thanks for your reply. As I stated in my first post, I know how to reset the brakes, but not how to set the amount. Using the stalk only allows me to reset to a higher amount that usually is less than 10,000 miles. So it will rest from 6,000 to 9,000. And every time it is a smaller amount. So prior to going to the dealer, it reset from 2,000 miles to 3,200. What tools are out there that will let me set a higher amount?
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10-19-2016, 07:00 AM | #4 |
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Don't think you can spec a specific amount to reset.
However, when you DO reset the light, the ECU is looking for a differential resistance in the brake wire. If it doesn't see this, this may be why you have issues with not having it set to 50,000 miles or whatever. I know when I did my sister's brake I tried to use the sensor and it threw a fit. Had to jump the wire. |
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12-05-2016, 04:06 PM | #5 |
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As mentioned above the computer is a little smarter than it looks.
It is actually looking for the brake pad circuit to be open and then closed again. I would disconnect the sensors. Power on the car and let it sit for a few minutes, and attempt a reset (obviously wont reset since they are disconnected). Then reconnect all the sensors, power up the car, and attempt to reset. I remember having to go through some weird process like that with my M3 to get it to reset fully. |
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12-20-2016, 07:11 PM | #6 |
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Any updates op?
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12-20-2016, 09:06 PM | #7 |
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The car predicts wear based on mileage driven vs time before the first wear wire was tripped. You can put new pads in all day but the computer will always think they are 75% worn once that first wear wire trips. If the second wire trips the dme thinks the pads are below 2mm and will throw a check engine light. Only way to reset the light at that point is to replace with a sensor that still has at least 1 wire still attached.
So, either live with the computer telling you your brand new pads have low miles left on them, or buy a brand new sensor and reset the computer. As is, the computer still thinks your old pads are in the car and that they will be down to 2mm within x estimated miles. Cheaper to just ignore the very inaccurate mileage estimate being displayed. |
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04-11-2017, 06:48 AM | #8 |
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Unless the CBS calculation has been thrown off due to your track usage. I've noticed that on some cars that have more frequent pad changes (eg. X5's that go through a set of front pads every 25,000-30,000km), when you reset it it also lowers the predicted remaining life. Whereas an equivalent vehicle that is driven more gently and spends a lot of time off the brakes (eg. highways) will usually get the maximum estimation. Having said that, the prediction is not always accurate and if you change the way you use the vehicle then the system tends to be even more inaccurate. There are a lot of factors which go into pad wear estimation. Brake pressure and braking duration are two examples.
We frequently get cars which come in with 'due' status on the brakes but they actually have heaps of pad material left. It's is very annoying and a waste of customer time and workshop labour. The dealer can 'recalibrate' the prediction by entering in the measured pad amount. Not sure about your market but we've been told not to do these corrections and instead let the CBS system sort itself out, at great nuisance to the customer. When did you last update the software in your car? A revised algorithm was released sometime in the last two years from memory. Have you also tried resetting the CBS for brakes after every track day? |
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09-24-2019, 03:14 PM | #9 | |
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09-24-2019, 03:15 PM | #10 | |
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09-25-2019, 12:54 PM | #11 |
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It's fairly straight forward to code all of this stuff off. If your car is a track toy just shut all these off, you should be servicing everything way more often than it suggests anyway.
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