I have an 08 Scion xb. One of the rear wheels is heating up and there is burning brake smell when I come to a stop. I pulled the wheel and off and the caliper was not seized. The tire and rotor turns freely. So something is causing this during driving. Would this be the caliper going bad or another brake system part like a valve or abs part?

 

Sounds like a seized caliper to me. Are you *sure* the caliper slide pins are not seized and can move freely? Try taking the caliper off and seeing if you can push those slide pins in and out freely. While you have done that, minus well pull them out and clean/re-lube them.

There is no other way for the wheel and rotor to get that hot without the brake being applied a long time. My theory is that they are sticking, but maybe not enough that the wheel is locked with the brake. If they drag hard enough, it will get hot soon enough.

I had seized pins in the back years ago... I had to buy new slide pins and now I pull them out yearly now to clean/lube them. I won't have that hassle again!