Odd Brake warning

spurcap · 02-10-2018, 12:19 PM

So recently bought a 2012 e70d but have owned a numbers of others bimmers in the past. From looking at car when I bought it all was okay. Checked CBS and nothing needing done

Fast forward a month....

Got warning on Idrive that brakes are at minimums and got red brake light on dash. Going into CBS rears are lower but still show like 15000 miles.

Looking at the pads they look low but okay. Dealer measured them to be in spec a month ago...

In the past on other cars this light always corresponded to a low miles on CBS so when warning came on I was expecting, replaced rotors and pads and sensor, reset CBS and all was good. Here I am not sure.

Could the PO replacing brakes and resetting CBS but not replacing sensor have done this?

Any idea on best first plan of attack? Happy to replace all corners pads and both sensors and reset CBS if needed but don't deally want to waste pads if they still have life...

Kdavis61 · 02-10-2018, 03:09 PM

Quote:

Originally Posted by spurcap

So recently bought a 2012 e70d but have owned a numbers of others bimmers in the past. From looking at car when I bought it all was okay. Checked CBS and nothing needing done

Fast forward a month....

Got warning on Idrive that brakes are at minimums and got red brake light on dash. Going into CBS rears are lower but still show like 15000 miles.

Looking at the pads they look low but okay. Dealer measured them to be in spec a month ago...

In the past on other cars this light always corresponded to a low miles on CBS so when warning came on I was expecting, replaced rotors and pads and sensor, reset CBS and all was good. Here I am not sure.

Could the PO replacing brakes and resetting CBS but not replacing sensor have done this?

Any idea on best first plan of attack? Happy to replace all corners pads and both sensors and reset CBS if needed but don't deally want to waste pads if they still have life...

If the sensors weren't replaced that'd be why the brake light is showing up, even if the pads are fine. They're a one time use sensor and need to be replaced along with the brakes. I'm not sure you can replace them after the fact, but someone else will chime in on that. If it were me I'd just change all four the right way, but I don't mess with brakes because I have family and friends in my car constantly.

*not that I believe it's a safety issue, but if the PO skipped that step, it would concern me a little*

jandref321 · 02-10-2018, 05:52 PM

It could be the sensor. I’d just swap it out and see what happens...too easy to remove the old one and just follow the same patch for the new one.

As long as you actually take care of your car and pay attention to pad levels then you technically don’t have to replace the sensor. It’s really basic...the sensor clips into the pad and is covered in plastic and when the pads wear down it rubs the plastic off and touches the rotor, triggering the brake light. The wires could also go bad or the metal snap that holds it in place in the pad could break and cause problems triggering the brake light. Otherwise you can just use the old one. As long as you never let the pads get so low that it rubs the plastic off the sensor.

I like buying kits because they usually come with new pads, rotors, sensors, lube, etc...but they don’t have full kits for the X5M because of the front rotor size unless you get an ECS kit. I forgot last time I swapped pads and ended up buying sensors and installing the next week, no biggie.

hennessy_r24 · 02-11-2018, 12:56 PM

What JANDREF321 said you need new pads, when the pads wear down it opens the bridge on the sensor "wire to wire contact" triggering the light. If you are the type of person that keep track of maintenance and check your rotor and pads every so often all you have to do is cut the wire and splice the ends or buy a new one and the conection is behind the wheel well liner.

mitch808 · 02-11-2018, 12:58 PM

The dash warning is an approximate. The sensor is an absolute, open or closed circuit. They are not on the same maintenance schedule.

When the dash says to check brakes, you inspect and reset it. If the sensor reaches its limit it will make a different error. And you SHOULD replace everything needed

hennessy_r24 · 02-11-2018, 01:46 PM

Quote:

Originally Posted by mitch808

The dash warning is an approximate. The sensor is an absolute, open or closed circuit. They are not on the same maintenance schedule.

When the dash says to check brakes, you inspect and reset it. If the sensor reaches its limit it will make a different error. And you SHOULD replace everything needed

He reset it

spurcap · 02-12-2018, 09:30 AM

Took off wheels, inspected pads. All greater than 10mm life.

Took out rear sensor and inspected - all looked good.

Tried to take off front, and the cable broke right where it connects to the sensor in the pad. I am guessing this somehow got worn and was not making good continuity. Given pads all have significant life, I twisted the front two sensor cables together, soldered and covered in heat shrink and hit away in the wheel well. No light anymore.

No warning of low pads either but I know how to key and eye on my brakes, especially given I change between winter and summer tires.

Next time the fronts need replacing I will put a new cable on but can't really think of a good reason to do so at this point even if the sensor is only $10.

02-10-2018, 12:19 PM	#1
spurcap Enlisted Member 5 Rep 34 Posts Drives: 2006 330i 2012 x5 35d Join Date: Nov 2012 Location: New Jersey iTrader: (0)	Odd Brake warning So recently bought a 2012 e70d but have owned a numbers of others bimmers in the past. From looking at car when I bought it all was okay. Checked CBS and nothing needing done Fast forward a month.... Got warning on Idrive that brakes are at minimums and got red brake light on dash. Going into CBS rears are lower but still show like 15000 miles. Looking at the pads they look low but okay. Dealer measured them to be in spec a month ago... In the past on other cars this light always corresponded to a low miles on CBS so when warning came on I was expecting, replaced rotors and pads and sensor, reset CBS and all was good. Here I am not sure. Could the PO replacing brakes and resetting CBS but not replacing sensor have done this? Any idea on best first plan of attack? Happy to replace all corners pads and both sensors and reset CBS if needed but don't deally want to waste pads if they still have life...
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02-10-2018, 05:52 PM	#3
jandref321 Captain 344 Rep 728 Posts Drives: 2012 X5M Join Date: May 2014 Location: United States iTrader: (1)	It could be the sensor. I’d just swap it out and see what happens...too easy to remove the old one and just follow the same patch for the new one. As long as you actually take care of your car and pay attention to pad levels then you technically don’t have to replace the sensor. It’s really basic...the sensor clips into the pad and is covered in plastic and when the pads wear down it rubs the plastic off and touches the rotor, triggering the brake light. The wires could also go bad or the metal snap that holds it in place in the pad could break and cause problems triggering the brake light. Otherwise you can just use the old one. As long as you never let the pads get so low that it rubs the plastic off the sensor. I like buying kits because they usually come with new pads, rotors, sensors, lube, etc...but they don’t have full kits for the X5M because of the front rotor size unless you get an ECS kit. I forgot last time I swapped pads and ended up buying sensors and installing the next week, no biggie.
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02-11-2018, 12:56 PM	#4
hennessy_r24 Private First Class 23 Rep 175 Posts Drives: bmw m3 Join Date: Sep 2010 Location: bergen county new jersey iTrader: (0)	What JANDREF321 said you need new pads, when the pads wear down it opens the bridge on the sensor "wire to wire contact" triggering the light. If you are the type of person that keep track of maintenance and check your rotor and pads every so often all you have to do is cut the wire and splice the ends or buy a new one and the conection is behind the wheel well liner.
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02-11-2018, 12:58 PM	#5
mitch808 Captain 107 Rep 994 Posts Drives: 2012 X5 35i Join Date: Mar 2014 Location: Seattle iTrader: (0)	The dash warning is an approximate. The sensor is an absolute, open or closed circuit. They are not on the same maintenance schedule. When the dash says to check brakes, you inspect and reset it. If the sensor reaches its limit it will make a different error. And you SHOULD replace everything needed
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02-12-2018, 09:30 AM	#7
spurcap Enlisted Member 5 Rep 34 Posts Drives: 2006 330i 2012 x5 35d Join Date: Nov 2012 Location: New Jersey iTrader: (0)	Took off wheels, inspected pads. All greater than 10mm life. Took out rear sensor and inspected - all looked good. Tried to take off front, and the cable broke right where it connects to the sensor in the pad. I am guessing this somehow got worn and was not making good continuity. Given pads all have significant life, I twisted the front two sensor cables together, soldered and covered in heat shrink and hit away in the wheel well. No light anymore. No warning of low pads either but I know how to key and eye on my brakes, especially given I change between winter and summer tires. Next time the fronts need replacing I will put a new cable on but can't really think of a good reason to do so at this point even if the sensor is only $10.
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