[drukpa]

Just got a 2011 x3 xdrive28i and while driving I noticed the car was slowing down as soon as I lift my foot off the accelerator, drove for around 5 mins and then slowed down in an intersection, when I tried to drive off it made a horrible sound and car won't move. Checked the wheels and both the rear wheels were too hot and could smell some burnt smell.

Turned off the car, pulled parking brake, started car released parking brake and still the brakes won't disengage. I let it cool down for about 20 minutes and pumped the brakes and then it would release and then it would drive normally.

This does not happen all the time, but once in 10 drives, happens randomly.

There are no lights on the dashboard.

Though it was stuck caliper but how can two calipers get stuck at the same time. Parking brake works fine.

Will air in the brake system cause this? Thought if there are faults in the ABS/DSC, it'll throw warning lights, but no lights come on at all.

[383vett]

Air in the system will cause the opposite. Brakes will not engage. Possibly a bad master cylinder or something wrong with the abs system. Sounds like you need a pro to diagnose.

[Dekero]

Hey I had this exact issue with a front brake caliper... It would lock up and not release until after shutting the car off and letting it sit for 15-20 mins...

Replaced the caliper twice thinking it was the issue.... Not the case..

Turned out to be a bad ABS valve body that had something contaminating it and causing that calipers brake line to lock up...

The fix:

Buy a used ABS/DSC PUMP AND VALVE BODY assembly off of eBay for $175, took the valve body and motor off of the new one and swapped it to the DSC computer part of the old one(This way it didn't need to be coded... And then did a full Abs brake bleed procedure Twice to clear any air...

That was 8 months ago and I've had no problems since...



Here are a few pics from when the caliper had locked up, how hot it got, as well as how I swapped the valve bodies..

Hope it helps, feel free to hit me up if you need any help.

https://photos.app.goo.gl/6Uf2BNqUPLVTqot88

[Dekero]

Any update on this?

Would be helpful to know if you're having the same.issue that I have had as well as about 3 others I'm aware of.... Clogged abs valve bodies on the F25 seem to be a common issue based on my research.

[drukpa]

Originally Posted by Dekero

Any update on this?

Would be helpful to know if you're having the same.issue that I have had as well as about 3 others I'm aware of.... Clogged abs valve bodies on the F25 seem to be a common issue based on my research.

Waiting for a scan tool to do a full scan of the car. You could be right with the ABS/DSC pump, if it had errors with the computer, think it'd show up on the dash, but nothing on the dash.

After driving few more times I think can now reproduce the problem. Coming to a stop have to press the brake firmly once and I can feel it locking, then do a complete stop and press the brake pedal all the way down, and it'll release. I even drove with the DSC off but the problem does not go away.

Anyway, going to do a full brake bleed, change all ABS sensors and see if it's still there.

[Dekero]

You're not going to have an error on the dash for the DSC there's nothing wrong with the DSC you've got something clogging one of the valves in the actual ABS valve body once it gets stuck in there after you've hit the brakes hard it sticks there until you tap it again and the pressure releases and it moves out of the way like I said the fix is to Frankenstein yourself a new DSC/ABS Valve body...

[mayhewt11]

I have the exact same problem for months. I tried everything until I came across this article. Interestingly, this started happening almost immediately after getting rear pads and rotors done by a local repair shop. I replaced - all rotors and pads (Again), brake master cylinder, bled brakes once, didn't expect this at all!

The locking up has gotten significantly worse, it seems to happen most often when accelerating at higher speeds and BOOM, right when let my foot off the gas, the brakes engage HARD. Imagine this happening on the highway and when passengers are in the car. It's happening almost every time I drive now.

Will follow up with results from this repair.

[tracer bullet]

Originally Posted by mayhewt11

Will follow up with results from this repair.

Would be interesting to know what you figure out.

I like the idea that something is allowing the pressure to be built up but then somehow not releasing it. If the front brakes don't do this, it may help pinpoint the issue, it knocks some of the possibilities off the list.

It was said air won't do this, but I'm not so sure. Of course if air is in the system, and you hit the brake pedal, the air will compress and you wont' get as much hydraulic force on the piston as you want. But also, that air can expand with heat, and begin to slowly apply pressure on those brakes. Not a lot, but perhaps enough to notice. I've had this happen with my mountain bike.

Good luck!

[E36M3]

Have you eliminated the hill hold feature as a potential cause?

[drukpa]

Originally Posted by Dekero

Any update on this?

Would be helpful to know if you're having the same.issue that I have had as well as about 3 others I'm aware of.... Clogged abs valve bodies on the F25 seem to be a common issue based on my research.

Thank you for your tip/help. As a last option I bought a used DSC module and changed the valve body/pump and installed it on the same computer. Bled the whole brake including the ABS/DSC with ISTA+. Haven't experienced any brake lock ups so far.

For others experiencing the same issue, I did the following before this without success:

- Disabled/disconnected parking brakes
- Disabled DSC
- Cleaned brake calipers, they were not sticking
- Changed the brake hoses
- Changed the brake fluid and did a whole bleed including ABS unit
- Auto hold was disabled
- Changed wheel speed sensors

[mayhewt11]

I can confirm this fixed my problem after a year of attempts, frankenstine a new ABS/DSC module to the computer portion of the one your car came with. Fluid purge and bleed, fixed. Bought one off eBay for $150