Hello, changing front and rear brakes on 2018 Camry XLE, front brakes went without issue. I'm new to the electronic brake caliper piston and having issues. I had removed both rear tires and removed one of the calipers. I tried to compress the piston and it did not work like the front brakes. I looked it up and it said to push the parking brake up three times then down three and hold. I think the first time i did this I messed up? I ended up getting to the point where the PARK was slow flashing like its suppose to be to go into "work on brakes" mode. So, now the rear passenger side piston look completely out and will not compress, I pulled off the caliper on the driver side and it worked(able to compress) as it was suppose to and I was able to compress it. I'm assuming I screwed something up since I might have messed up putting it in the "work on brakes" mode with the caliper off? I also found something on trying to get the motor to retract by using a battery and connecting to the leads on the brake motor, this did not seem to work, still not able to compress the piston. Any help would be greatly appreciated.



Thanks

Gene

 

Not up to speed on the electric p-brake.

As stated, the car needs to be put into service mode or such. This action is supposed to move the piston inward however it appears the piston does not retract all the way in. The piston may be needed to be rotated to screw it back into the caliper to install the new thicker pad. This action requires a tool that engages the piston to rotate it. YouTube has video's of using this tool.

It may be possible to bypass the cars p-brake computer programming to retract the piston by connecting DC voltage directly to the caliper electrical plug. The direction of the polarity will determine the direction of it motor to move the piston in or out. Not sure the voltage but assume 12V DC.

Try rotating the piston to move it inward. You may not be able to manually push the piston in because it is a screw jack system. The combination of the motor screwing the piston back and manual rotation is what moves the piston.

 

Thanks, I had already done the above(both using a battery and jumping the motor and also removed the motor and tried to manually retract it. Neither moved it. It seems that there is not a "fail safe" that would stop the screw or whatever is pushing out the piston/plate and since the caliper was loose and not on the rotor it had too much room and disconnected? Thats the only thing I can think of since it will not retract. I ordered a new caliper, since that seems to be the only way to fix it. I learned my lesson.

 

Seal kits and pistons for this electric brake caliper are available for DIY rebuild. Suspect the piston needs to be pressed into the caliper while the motor is running in retraction mode to engage the piston threads on the motor screw shaft.