Hi all,
my 2015 Hatchback has an active brake issue. Basically, the car brakes for a split second (front right wheel) without me pressing the pedal. It happens only when it rains or when I quickly release the gas pedal. My understanding is that, under those conditions, the active brake "primes" the brakes by bringing the pads closer to the disks in order to shorten the response time in case you really want to stop. Problem is that instead of bringing the pads closer, it does actually touch the brakes. It's a tenth of a second but enough to freak me out every time. It only happens above 40-45 mph. My nearest dealer is 200 miles away...
Anybody has ever had a similar problem? Shops around here do not want to deal with it.

Help! I can't keep on driving my wife prius :((

Thanks
Stefano

 

Since the issue appears to only be the right-front brake, I would suspect either corroded pad to caliper interface that is not allowing the pads to relax off the rotor the intended/expected amount or a 'sticky' caliper piston that would create a similar situation or the caliper slide pins are sticking. I would pull the pads/calipers off to check/clean/lube the easy stuff first and go from there. Let us know what you find.

 

Hey V8, thanks for your suggestion. I had it checked by a professional that deals mostly with German cars (well respected professional around here). He did not find anything simple. We tried an hard reset of the electronics but no success there either. I understand he even run some videos but was not able to catch the effect on camera. Maybe it's too fast or the camera was not fast enough.
I admit I cannot guarantee it's only the right front wheel. Car does pull to the right but maybe it's on the 4 wheels but harder on the front right one. My next step is to contact the nearest dealer (200 or 300 miles... pick one) hoping that in their global network there is somebody with a similar experience.

 

hi did you find out what it was??

my 2015 mini cooper s is having the same exact issues, took it to the dealer and they haven’t found anything !!

help please

 

The electronics that controls the ABS and the whole braking. Had to change it. More than 3k. Do not waste your time with brakes or anything else. I've been told it's not worth reprogramming.
Hope it helps
Stefano

 

if you could share with me what are the parts you replaced ?
😭😭😭😭😭 my dealership it’s not helping at all, like they said there’s nothing they can find.
so useless this people ever tho I already paid $4000 on repairs that didn’t fix the issue

 

I think it was the EBCM Electronic Brake Control Unit. Brakes are mechanically controlled by an hydraulic unit. The issue, in my case, was the electronics controlling the hydraulic unit. This control unit might be fitted to the hydraulic unit in one single part, the EBCM.
I asked to reprogram the unit but they suggested to replace the part. I also tried to find an used one but with no success. I don't remember why but it made sense to me at the time.