[pragueX5]

Hi guys, is there any way to find out the brake pad remaining wear / service interval?
All my previous BMWs had this in idrive menu.
The G05 has only oil.
I am at 40k km so I expect the pads to he dobe soon.

is it just that the warning light will come up for the last 2k remaining or what?

thx

[volodp]

I was going to say that because 45e uses not only brake pads but also regenerative braking, it's much harder to predict when the pads/disks will have to be replaced. But then I noticed you have a 40d. Damn. Must be something else then. I was also initially puzzled seeing that it's missing.

[Flying Ace]

Interesting I just noticed this since you have mentioned it. Why does BMW not give us a CBS estimate for this? There's definitely a brake wear sensor. I would say that should the sensor trip a brake light should pop up, but a CBS estimate would be very useful to anticipate servicing.

To answer your question, my approach would be to measure rotor thickness. Traditionally on BMWs when rotors are ready to be replaced, pads are replaced at the same time.

[jad03060]

How long your brake pads last varies, sometimes radically, by where and how you drive. Drive lots of miles on limited access highways, and you will go a very long distance between ever needing to use your brakes. Drive in heavy traffic in a city, you might be stopping every few feet. If you're one to approach a stop and brake at the last moment versus coasting up to it after determining you must stop smoothly, and your brake use will be again, radically different.

I don't think there's logic in the vehicle to account for those variables like there is for say oil life where it's easy to keep track of engine on time and miles driven. The vehicle already keeps track of your average speed, and that plays into oil life.

IOW, I'd be surprised if the vehicle made an estimate on brake life remaining. It's fairly easy to check the existing thickness of the pads through a visual inspection, though, and that is probably a more reliable assessment. Depending on the wheels you have, you may be able to do that without removing the wheels.

The brake wear indicator is basically just a wire embedded in the pad...when the pad wears down enough, the wire gets grounded, which turns on a light as it exposes the wire to the metal of the rotor. Pretty simple and basic, used by numerous companies.

[pragueX5]

I am not discussing break pad lifetime here. But the fact that BMW like 10yrs back had Break pads estimate in Idrive menu and now G05 doesn't. anyone?

[volodp]

Originally Posted by jad03060

IOW, I'd be surprised if the vehicle made an estimate on brake life remaining.

But they really had it before. F15 had it and I'd even say that my E61 from 2008 had it too. And it seemingly worked exactly as with the oil change predictor - if I would do many highway miles - it would go down slower and if I used an emergency braking function - it would subtract a 1K straight away. I guess regenerative braking as a part of a mild hybrid drivetrain could introduce another level of complication in terms of being able to predict this thing and its precision would be so low that it won't make any sense to display it.

[LogicalApex]

Originally Posted by volodp

But they really had it before. F15 had it and I'd even say that my E61 from 2008 had it too. And it seemingly worked exactly as with the oil change predictor - if I would do many highway miles - it would go down slower and if I used an emergency braking function - it would subtract a 1K straight away. I guess regenerative braking as a part of a mild hybrid drivetrain could introduce another level of complication in terms of being able to predict this thing and its precision would be so low that it won't make any sense to display it.

I am new to the brand, but they seem to have dropped this on all the newer cars. I wonder if it is due to them finding out the algorithm wasn't accurate enough and they wanted to reduce the need to replace pads prematurely under prepaid service agreements...

As I have read a fair number of posts on the forum for cars that do have the feature getting iDrive notes to replace the pads even though the pads aren't worn a visual inspection...

The wear sensor is more accurate as it aligns perfectly with them point where they'd be willing to pay for the replacement (for people who have that).

[volodp]

Originally Posted by LogicalApex

I am new to the brand, but they seem to have dropped this on all the newer cars. I wonder if it is due to them finding out the algorithm wasn't accurate enough and they wanted to reduce the need to replace pads prematurely under prepaid service agreements...

I don't think this was happening at all (them having to replace the pads prematurely). They always had the wear sensor and only that triggered "replace brake pads" message. An iDrive prediction system would be just that - a prediction, and sometimes it would count down to 2000 km and would stay there for a long time until the sensor would get triggered. So it might rather be that the algorithm wasn't precise enough to be useful in the long run. That I could easily believe. Because it's true that a prediction like that is very complicated - not only it has to take into account past driving history but it would also have to anticipate things.

[jad03060]

Didn't some wear sensors have essentially two leads? The first one triggered the 'the pads are getting low' warning, and the second one implied "DO IT NOW!".

[volodp]

Quite possibly so.

[SWBOS]

Out of interest, would anyone know how much lining is on the brake pads (or perhaps the service dep't quote disc thickness) from new?
I have a little over 23k on my X5 and each time it has come back from service it seems to still have 10mm remaining.... It's either odd or that these things are made from something that just doesn't wear out!

[2019x5User]

Originally Posted by jad03060

Didn't some wear sensors have essentially two leads? The first one triggered the 'the pads are getting low' warning, and the second one implied "DO IT NOW!".

Are those sensors available?
Mine is over 64000+miles , haven’t seen it yet.

[eelnoraa]

Originally Posted by 2019x5User

Are those sensors available?
Mine is over 64000+miles , haven’t seen it yet.

Lol. 🙃

Brake sensor is just a piece of wire. When pads get thin enough, the wire is grinded. Once wire is broken, brake replacement warming is lit. You still have a bit of time to change. No such a thing as 2 stages warming. It is all imagination as usual.

BMW sensors are on front left and rear right wheels, inner pad only. I would visual inspection the pad thickness for all corners, should be easy to see for outer pads. If they look good, no reason to preemptively change brakes. How long brake last is heavily a function if driving habit. No rule of how many mile it must be changed.

[jad03060]

Some models had some logic that used just miles traveled to could turn a brake wear warning on (yellow) when it thought there was about 3,000 miles left…but it could sit at that level for ages, but would turn to red once the sensor’s wire actually had the pad worn down enough. Typically about at 3mm of pad thickness (8mm new, depending on the type). So, you might see a symbol come up when it thinks there’s 3,000 miles left, but the actual wear indicator is the real thing. 3mm is about the minimum thickness, but if it’s a commercial truck, they mandate more.

If the red brake wear indicator comes on, you should try to make an appointment to replace the pads fairly soon, but a yellow one…you have a bit more time to work it in.

[eelnoraa]

No reason for useless discussion with someone who has never done a brake job.

Here is a picture of a brake sensor connector. There are only two pins. It is either connected, or disconnected. People can judge how many stage the sensor is capable of having.

[BlkGS]

Originally Posted by eelnoraa

No reason for useless discussion with someone who has never done a brake job.

Here is a picture of a brake sensor connector. There are only two pins. It is either connected, or disconnected. People can judge how many stage the sensor is capable of having.

There's two pins, so clearly there's two stages, right? Everyone knows that you only need one wire for electrical devices to work! :P

We joke about this but there's probably a lot of people who think a USB is one wire so why wouldn't other things be like that too, or just have no idea how electricity or anything else on a car works.

[streborx]

It would be possible, of course, to design a 2-wire brake pad wear sensor that changes resistance with wear, thus providing a continuous or incremental indication of pad thickness, but fortunately the auto design engineers haven't burdened us with yet another complexity, prone to failure and misleading information.

[eelnoraa]

Originally Posted by BlkGS

There's two pins, so clearly there's two stages, right? Everyone knows that you only need one wire for electrical devices to work! :P

We joke about this but there's probably a lot of people who think a USB is one wire so why wouldn't other things be like that too, or just have no idea how electricity or anything else on a car works.

No. The sensor detect the continuity between two pins. Conducting, brake is good. Disconnected, brake need to be re place. To have 2 stages, you need 3 pins.

[eelnoraa]

Originally Posted by streborx

It would be possible, of course, to design a 2-wire brake pad wear sensor that changes resistance with wear, thus providing a continuous or incremental indication of pad thickness, but fortunately the auto design engineers haven't burdened us with yet another complexity, prone to failure and misleading information.

Brake sensor is located in an extreme harsh environment. Wet, dry. Extreme cold, extreme hot, metal condemnation …. Detecting resistance in theory works, but as your said, it will be very complex and very unreliable. Fact is it is not implemented that way.

Thr estimsted miles left is really just like driven when sensor tripped, then extrapolate. It is en estimation. Not a 2nd detection.

[BlkGS]

Originally Posted by eelnoraa

No. The sensor detect the continuity between two pins. Conducting, brake is good. Disconnected, brake need to be re place. To have 2 stages, you need 3 pins.

I was totally kidding. Extreme sarcasm. It's clearly a "when this circuit breaks the sensor is triggered" device.

[eelnoraa]

Originally Posted by BlkGS

I was totally kidding. Extreme sarcasm. It's clearly a "when this circuit breaks the sensor is triggered" device.

Oh I mis-read entirely. I should have known you know better 😂

[BlkGS]

Originally Posted by streborx

It would be possible, of course, to design a 2-wire brake pad wear sensor that changes resistance with wear, thus providing a continuous or incremental indication of pad thickness, but fortunately the auto design engineers haven't burdened us with yet another complexity, prone to failure and misleading information.

No, the way to do it would be to have the contacts connected to a digital circuit that monitors for ground, and then latches. The wire would touch the rotor, go to ground, then trigger the system. You'd then need a way to unlatch it via software after replacement.

Resistance monitoring would be way too finicky.