Try opening the bleeder valve on brake caliper in question, see if brake will release. You can follow brake bleeding procedures. Turn key off, disconnect abs actuator and control unit connector or negative battery cable. Connect a transparent vinyl tube and container full of proper brake fluid to air bleeder valve.
Fully depress brake pedal several times. With brake pedal depressed, open air bleeder valve. Maybe that will release the brake pressure. Close valve.
Also, Take the wheel off, make sure there is no ice or anything frozen.
Sunday, February 10th, 2013 AT 6:26 PM