Breaks wont let go! Hill assist not working properly

[NormDriver]

So Ive had this problem ever since I got the car. Whenever hill assist is on and Im on an incline, it will hold the car but then it would't let go if I go forward and my brakes would drag. Sometimes when I would turn it off in the settings it would release the brakes but sometimes I would have to go under the car and release some brake fluid to let the brakes go. Such a pain to do when driving. Also when I do fairly aggressive braking the braks seem like they start sticking and not letting go. Ive already replaced my brakes because they got so hot once, they overheated and cracked the pads. All the guide pins move smoothly and i have no lights on the dash. The only thing I get is "immobilizer malfunction, service soon", but I think that has nothing to do with it, since the car drives normaly. I get that warning on a cold start and it rings on and off for a couple minutes and goes away (really annoying). So Im very confused and desperate for help. I drove for a couple months strait with no problems and then it comes back (hill start assist never worked, and would't let go of the breaks). Its always bothering me because I never know when itll lock up at the next stop light or something.Planning to go to the dealer tommorow, but thought I would look for help before I go in.

 

[cxwrench]

Nothing to add but do your realize you called them both brakes and breaks? And went back and forth between the 2 at least 4 times?

 

[DAPR]

Hey it gets confusing when you break your brakes.

 

[CarGuy]

Hey it gets confusing when you break your brakes.

Lol

Sent from my SM-N950U using Tapatalk

 

[DangerMouse]

No idea but glad you are finally taking it in. Keep us posted on the outcome.

 

[NormDriver]

No idea but glad you are finally taking it in. Keep us posted on the outcome.

Ran out of time today but will try to go this week. Driving so so nerv racking.

 

[tbST14]

So, what was the outcome? I have this same problem almost exactly as you describe on my 2014.
Where the brakes will hold even going forward until i tap them again, then they let go.

When I took out fuses 1 and 9, I did not have the problem so i think it is related that circuit. Plus sitting inside the car and toggling the hill assist on and off changes the behavior slightly, like it wants to let go but does not fully.

I've already had one set of calipers replaced because the dealer thought they were grabbing, but then this is also after the replaced the rotors because they thought the lip was grabbing and I brought it back because it wasn't fixed. $1500 later and I still have the problem.

 

[FiestaSTdude]

I didn't know the fiesta ST had hill start assist

 

[Capri to ST]

I didn't know the fiesta ST had hill start assist

You can turn it on and off in the vehicle settings on the Sync 3 screen. On my car I believe vehicle settings are on the second page of the settings menu, the one that you have to swipe over to get to.
I have driven nothing but manual transmission cars my whole life, but I still find it helpful.

From the manual-
Using Hill Start Assist
1. Press the brake pedal to bring your
vehicle to a complete standstill. Keep
the brake pedal pressed.
2. If the sensors detect that your vehicle
is on a slope, the system will be
activated automatically.
3. When you remove your foot from the
brake pedal, your vehicle will remain
on the slope without rolling away for
approximately two or three seconds.
This hold time will automatically be
extended if you are in the process of
driving off.
4. Drive off in the normal manner. The
brakes will be released automatically.

 

[Stevesims]

Do't mean to hijack the thread but having Hill assist issues as well in my 2016 FiST. It mainly happens when the car has been sitting for an extended period like first thing in the morning when I back out of the garage. If I tap the brake pedal a time or two it releases the "lock" and it is generally fine the rest of the day. Occasionally, when I leave work later in the day, it will stick again. It always happens after I reverse. Hill assist works normal when I start on a hill, and the lock up occurs when the Hill assist is on or off in Sync. Any thoughts?

 

[SteveS]

Could it be that you are actually experiencing sticking from light surface rust on the rotors?

 

[Stevesims]

Could it be that you are actually experiencing sticking from light surface rust on the rotors?

I don't think so. I probably should have clarified... When I say sitting for an extended period of time, I am only talking overnight. I also park in a garage, so humidity in FL doesn't have a chance to set up any surface rust in the 12 or so hours it sits. When I reverse out of the garage and come to a stop, I slide the shifter into 1st and start to go forward, it feels like the emergency brake is engaged. The car rolls out of the garage in reverse with no friction at all, but as soon as I start to go forward it is locked up. A quick tap on the brakes gets it to release, sometimes I have to tap twice. Also, the ground is almost perfectly flat, so incline is not a concern and the hill assist still works as it should when I start off at a light that is on an incline.Occasionally, it will do the same thing when I go to leave work, but at that time I only drive forward (meaning I back into a parking space, so reverse isn't used).

 

[Magnetic]

Following out of curiosity...

 

[tbST14]

So, what was the outcome? I have this same problem almost exactly as you describe on my 2014.
Where the brakes will hold even going forward until i tap them again, then they let go.

When I took out fuses 1 and 9, I did not have the problem so i think it is related that circuit. Plus sitting inside the car and toggling the hill assist on and off changes the behavior slightly, like it wants to let go but does not fully.

I've already had one set of calipers replaced because the dealer thought they were grabbing, but then this is also after the replaced the rotors because they thought the lip was grabbing and I brought it back because it wasn't fixed. $1500 later and I still have the problem.

I finally had mine fixed, and posted the parts tried and the final part that fixed my issue here (#57) on this thread: https://www.fiestastforum.com/threads/need-help.19707/post-483502

 

[stascom]

The ABS is a good starting point since it does it on its own. First thing I would've done is disable the ABS and see, if the issue is gone.

 

[tbST14]

The ABS is a good starting point since it does it on its own. First thing I would've done is disable the ABS and see, if the issue is gone.

I removed the fuse the first time and thought it went away. Then I did it again 2 weeks later (before the repair) and it still persisted, so removing the fuse in my case was not a conclusive indicator of a solution.