Disk brake sticking

This girl I know asked me why her back wheel locked up when she tries to back up. It is a disk brake and she said it just started doing it. You guys have any ideas? pads? Not hers the trucks.

what year/model truck?

Edited: 5/16/2006 3:10:04 PM by lowdyme

it could be a few things she only feels it when backing up not at all when driveing foward? since its disc it can only be a few things it could be a bad floater in the caliper if it has floating caliper and it is stuck on or only after applying the brakes or it can be a stuck e brake cable or just a bad caliper all together it might be the pads to but i dont think so the pads will move as much as the caliper will let them.

if its a disc, had as the lil drum shoes for parking brake, i gaurentee its that. is it a ford?? lol