Hyper extended parking brake piston while caliper removed; 2021 Kona EV

[navguy12]

Situation: My wife's 2021 Kona EV. My yearly R&R of the winter tires with the all seasons; also my yearly lubrication of the brake calipers/caliper slider pins. I did a Homer whilst the rear left caliper was removed...I set the electric parking brake and naturally the piston hyper extended.



So, I manually screwed the piston back into the caliper, put everything back together and turned the car on and off several times...

...but I still have a Christmas tree full of brake system warning lamps that I don't know how to extinguish.

Also, I can hear the brake e-master cylinder clicking whenever I apply the brakes...

The car is drive-able, but brake regen is not being allowed, and I suspect the anti-lock system is also not being allowed.

I booked an appointment (for 1630 on 11 Apr 2023) at the local dealer; the service guy right away is saying it will probably need a new caliper.

Anyhow: does anyone here know of some magic trick (I don't have an OBD2 tool anymore) where I can reset the system (such as a series of brake pushes and signal stalk pushes) via some home-mechanic hack?

Thanks.

 

[Genevamech]

If you have an appointment at the dealer - or any service shop really - the WORST thing you can do it try to reset the codes yourself. The shop will need those codes to figure out exactly what happened. Often** clearing the codes will also put the car in a special mode where it's re-doing diagnostics for some amount of miles or restarts which can also hinder diagnostics.

My advice is to just live with it the next couple days and drive it as little as you can. If they recommend a new caliper and you really believe that's not necessary, you can always decline that and just tell them to put the car back together and clear the codes for you.

(**This is definitely the case with ICE vehicles regarding emissions controls features, which are numerous, dunno how/if this applies to EVs. Better safe than sorry though.)

 

[navguy12]

Yes, its not being driven until I bring it in Tuesday.

If they can clear the codes and then do a simple test drive to confirm serviceability, so much the better.

At the end of the day, it’s just another valuable lesson learned.

 

[electriceddy]

I manually screwed the piston back into the caliper

Not that I would attempt this but apparently performing EPB in "brake pad change mode" allows the pistons to be pushed back manually after full retraction. The system is disabled until apply release function is executed 3 times. (of course using scanner)...see this video @ 1:35

Maybe this is the "magic trick" you are looking for, and possibly required when you take in for diagnostics.
Hope that helps

 

[navguy12]

Not that I would attempt this but apparently performing EPB in "brake pad change mode" allows the pistons to be pushed back manually after full retraction. The system is disabled until apply release function is executed 3 times. (of course using scanner)...see this video @ 1:35

Maybe this is the "magic trick" you are looking for, and possibly required when you take in for diagnostics.
Hope that helps

Thanks.


FYI: in the video the rear pads aren’t “stuck” because of corrosion, they are “locked” in place by small (think fish hook) one way barbs in the pad retaining clips. I use a fine set of needle nose pliers to compress one of the barbs enough to allow the one pad end to pass over it and come out of the retainer clips..

 

[navguy12]

Closure: the dealership just needed to connect their computer and clear the codes.

System now operating in accordance with manufacturers specifications.

$CA197.69.

Still much cheaper than paying them to do the routine brake servicing.

 

[hobbit]

Isn't "screwing" the piston back in a very different action from simply pushing it in without rotation?

I was able to push my rear calipers in a bit to open the gap wider while trying to track down why the
rears seem to make dragging noises so often; it's also useful to be able on a quick check for how
the caliper pins are floating when just making sure they move easily without taking things apart.

_H*

 

[hobbit]

Well, as I go through that video, which could have been ten minutes or less... those little retainer tabs on the spring
clips can be tricky to get the pad end past, I do note that ... and while he uses antiseize on the clips, he doesn't
seem to use anything on bolt threads, which is probably why he has trouble with disassembly, and is about the
only reason the slide pin would ever spin along with its bolt.

Makes me kinda wish I had a bead-blaster setup, though..

_H*

 

[navguy12]

Isn't "screwing" the piston back in a very different action from simply pushing it in without rotation?

I was able to push my rear calipers in a bit to open the gap wider while trying to track down why the
rears seem to make dragging noises so often; it's also useful to be able on a quick check for how
the caliper pins are floating when just making sure they move easily without taking things apart.

_H*

It is a totally different action, but AFAIK it is a typical way to move the piston on any of these e-brake type emergency brakes. Of course, YMMV.

 

[navguy12]

Post script: my wife complained about hearing a "hissing noise" when the service brake pedal was applied.

Confirmed the noise was coming from the e-booster/master cylinder area.

I brought it back in to Hyundai, I recommended they do a brake bleed (replaced all the brake fluid) and that solved the issue.

$432.67 for two hours of labour and brake fluid.

 

[electriceddy]

Post script: my wife complained about hearing a "hissing noise" when the service brake pedal was applied.

Confirmed the noise was coming from the e-booster/master cylinder area.

I brought it back in to Hyundai, I recommended they do a brake bleed (replaced all the brake fluid) and that solved the issue.

$432.67 for two hours of labour and brake fluid.

Probably better (and cheaper as it turns out) to have taken it in for service in the first place.

 

[navguy12]

Probably better (and cheaper as it turns out) to have taken it in for service in the first place.

For this one time, yes.

I’ll never make the same Homer Simpson error again.

…But they charge $345.00 plus HST for routine brake servicing (i.e. once a year caliper lubrication), so I’m still at less cost than two years of having the dealership lubricate the calipers.

 

[electriceddy]

they charge $345.00 plus HST for routine brake servicing

The same brake service was $219.95 on my 2nd year maintenance last October (called "A service 3 EV) which included other inspections and tire rotation.
I also had the gearbox oil changed again at the same time for an additional $79.95 (Labor only as I supplied the magnetic plugs and the oil).
Wheaton Hyundai has been pretty good to deal with...so far. Hopefully that remains consistent.

 

[Marco78]

I guess this methode in the video also works for the KONA.
Simply supply the electromotor with power.