I have a brake problem right now on a 2019 Hyundai Santa Fe with 17" wheel rims. After 150,000 km (93,000 miles), I changed the front and rear brake pads. The front brake piston calipers compressed with no problems allowing the installation of new brake pads but both rear brake piston calipers would not compress. I had to slightly turn the caliper piston on both rear calipers to allow the pistons to compress and allow the installation of new brake pads. Afterwards, the brake pedal returned to a firm, hard position and no brake lights appeared and the brakes seemed to be working normally. I noticed after 2 months that the front caliper and pads seem to be operating OK and the rotors had a clean shiny surface due to brake pad contact but both rear rotors are developing an ongoing rust buildup and I suspect that both rear caliper pistons are not compressing the rear brake pads hence the steady buildup of corrosion/rust on the rear rotors. My plan is to remove the rear brake pads and reinstall. Any reason for the rear caliper pistons not compressing and do you think I damaged the rear caliper pistons by turning them?....Any suggestions would be helpful.

 

I have not seen a 2019, so I don't know if there is anything weird about them, but I would re-do the rear brake process and put everything back to the original orientation - except with the new pads of course.

When you say that the pistons would not compress (like I presume that the fronts did) did you have the master cylinder open with a rag to catch any overflow?

 

I have noticed other Hyundai owners, other years & models posting the exact same problem. Brake Problem - Front Calipers will compress but Rear Calipers will not compress.

 

What are doing to try to compress the piston? I use a large C clamp pushing on an old brake pad to compress the piston without damaging it.

 

After doing a lot of research, I have discovered that certain late model Hyundai vehicles including the 2019 models have attached to the rear calipers an electronic parking brake system.

The rear calipers require the rear electronic parking brake system to be disabled to allow the caliper pistons to be compressed and the rear electronic parking brake system needs to be reactivated after changing the brake pads .

Trying to compress the rear caliper pistons without disabling the electronic brake system could damage the calipers.

There are some good videos on YouTube that address disabling the electronic brake system when changing rear brakes on Santa Fe 2019.

 

Very interesting !! Thanks for posting ! Hopefully your reply will help someone else.