I was changing my rear brake pads and noticed I could not get the caliper to open up wider so I could put the new ones on. I called the dealer and they said I have to bring it in so they can hook up their computer and tell the parking brake to open or release. It seems very proprietary and I am surely not the only person to change their own brakes before. Any recommendation on how to bypass this or something I can buy online that will allow this function. #NOTACHEVY
Thanks all.

 

The parking brake has ZERO to do with the calipers. Contrary to older model systems, the pistons on the rear calipers must be Rotated inward and NOT CLAMPED to collapse them. I can't remember the diameter of the brake tool required, but I believe that the generic tool that can be rented by thousands of auto parts stores do NOT have the correct size to fit.
What I do is use a sturdy pair of Long-Nosed pliers, opened to have the nose tips fit into the indents on the inside of the brake piston, and rotate them by hand. Sometimes it takes quite some pressure to do this, so I use an assortment of other tools, locking pliers and pads to save my tender hands.
You DO need to assure that you do have the parking brake released to do brake work, but since you evidently already have the caliper off, that point is moot.

 

You might want to check the brake fluid in the master cylinder. If you or someone has added more fluid,during the life of the pads, it might be overfilled to the top, making the manual compression of the wheel cylinder next to impossible.

 

The parking brake does have something to do with the calipers,so before starting work make sure the parking brake is not engaged. Like any other caliper with incorporated parking brake, mechanical or motor-driven, the wear in the pads is taken up by a ratchet system and the piston has to be pushed back while turning before fitting new (thicker) pads.

Obviously, too much brake fluid in the header tank could overflow when pistons are pushed back but there is little chance that it will stop the piston from screwing back. There will be some air to compress and the caps are usually vented. It is good practice to take some fluid out or drain some through a bleed nipple to avoid spilling brake fluid into the engine bay.

 

Fit a clamp on the flexi hose & a bleeder on the nipple before opening it & working on the piston.

The piston will retract much easier & you'll get no spillage

 

Fit a clamp on the flexi hose & a bleeder on the nipple before opening it & working on the piston.

The piston will retract much easier & you'll get no spillageDONT put a clamp on the flexi line if its fitted with braided lines you will crease the line

 

Old thread, but here's my story:

I let the brakes goo too long without service, though they had pass Virginia inspection in March 2020. I knew something was gooched when I had to take a small pry bar to get the RR pads/caliper loose. Piston was almost 100% out. About 1/6" to 3/32" of meat on the pads. I have the 3/8" cube tool to push and turn clockwise the piston. Just a PITA. I borrowed a real piston turn tool from a local parts store and had the piston back in place withing 8-10 minutes. BTW, I took the cap off the brake fluid reservoir and using an old, but clean turkey baster took out an ounce or so of BF. All went well thereafter. If I had not been stubborn this 4 hour debacle could have been cut in half. Lessons learned.