Electronic parking brakes and a strange thing that Hyundai Does...

Car came in the shop the other day needing brakes all the way around. It was a high mileage, for the year, 2021 Hyundai Santa Fe with electronic rear parking brakes. For those of you who don't know electronic parking brakes require being placed into service mode in order for you to be able to change the brake pads. Some vehicles you can do this through the radio in the car but a great many require a updated/newer style diagnostic computer in order to enter this mode. Some manufacturers have issues with certain cars so sometimes you need multiple different manufacturers tools in order to have complete coverage. This is a story about how there is more to understand about these systems manufacturer to manufacturer.

In this instance the tech, having put the vehicle in service mode, still could not get the caliper to fit over the new pads. It was almost as if the caliper piston refused to go back all the way as the piston was not flush with the housing as is the typical state when fully retracted. After putting it back into service mode again we were finally able to get the piston to fully retract and get one side back together. When the tech went to the other side to put the brakes together he found that the piston had extended literally as far out as the electronic brake caliper could force it to be. It was pushed back in just like the other side so what the hell happened?

As it turns out that even when put into service mode Hyundai still allows for the vehicle to try to engage the electronic parking brake if it sees wheel movement. Once the brakes and the wheel were put back together on the other side they had been rotated by the tech inadvertantly causing the vehicle to apply the parking brake and forcing out the piston on the other side that was completely torn apart previously. This was a case where being able to reinstall a caliper piston, something that has not been common place in this industry in over 3 decades comes in handy. Off the car we were able to repair the caliper, reinstall the electic motor and put back on the car without having to replace a 500 dollar OEM Caliper.

Just some strange diagnostic information that I hope helps someone else out down the line somewhere out there in the world.