Ok one the ABS system does not apply pressure it releases it, the ABS block has 4 valves called dump valves in it and when you go into ABS mode ie ( panic stop ) it will release the pressure in pulses to the wheel that is locking up, you may already now that , just refresh purposes. now the only way for the caliper to jamb up is heat and the caliper slides to cease up and even to brake pad uneven wear. also brake torquing can sum-times cause this, not often though.
---------- Post added at 02:10 PM ---------- Previous post was at 02:08 PM ----------
check to see if the piston turns in ez or not, if not replace it.