Both sides of my rear brakes are dragging. It doesn't seem to be the calipers. I jacked up the car and put the car in park, and there is some drag. I put it in neutral and there was a lot of drag. I noticed it the first time a few months ago after driving the car, and the left rear disc was very hot. Then, I drove home and it didn't get hot at all and it was cool to the touch. Occasionally it will drag and occasionally it will not.
Could it be electronic? I checked the brake pads and they are wearing mostly even. The passenger side was not as worn, but it also has not been dragging as often as the driver's side has. Which is why I feel like it is not the master cylinder. I disassembled and reassembled the passenger side. The slides seemed like they are not the problem, but I cleaned them. The ears on the pads and the clips were heavily corroded, so I cleaned them up as well so they are able to move more freely. I had to pry the outside pad off of the rotor as it was riding very close and dragging the rotor.
I talked to a local mechanic, and they said that they see a lot of cars with disc brakes that just get corroded and then won't release off the rotor, which is caused by the road salt and moisture. I am going to take the wheel off of the passenger side and see how that looks. I may try to readjust the pedal/pushrod to make sure it is not too tight. I took apart the driver's side and I noticed that the outside pad was worn a lot more than the inside pad was. The ears were also more corroded on the outside pad. I did not adjust the caliper since the 2012 Taurus requires the proper tool to twist it back in.
I might install new pads and pick-up the tool to adjust the caliper back in. Should I install new rotors? Any other ideas?
Based on your description, it sounds like your parking brake may be locking up on your rear brakes. I would recommend having your rear brakes disassembled and, using the special tool you referred to, try to compress the caliper. If the caliper is very difficult or refuses to compress, the caliper is sticking up and will require replacement in order to fix the problem.
It is not a requirement, but it is a good idea to replace all brake parts in pairs. With this in mind, it would be a good idea to replace both rear calipers. For best results, ensure that this job is performed by a certified mechanic.