Had the same issue....the problem was not caliper...it rarely is.... is it usually the slide pins that, well, do not slide anymore.. also the rubber protecting them usually gets thorned and water can get in... causing rust and swelling of the pin which stops moving... Then you,re stuck with just one side applying pressure on your rotor.
Go check, and then buy from nissan a rubber brake seal rebuilt kit and new slide pins... well worth it.
http://www.courtesyparts.com/pathfinder ... _4807.html
You will need part number : 41000L for the seal kit and 41217 or 41271+A depending on the one that is stuck.
S.