Q: I have replaced the break pads, calipers, and rotors on my 2003 ford explorer. My breaks keep locking up. I have also replaced the master cylinder.

Check the combination valve on the brake system. If the valve is sticking, then the fluid could be getting trapped and not returning. To check this valve, loosen the brake line on the back side of the valve (the side to the calipers) and see if the calipers move. If they do, then the valve is sticking. If they do not move, then the ABS module is sticking. If you need further assistance with yourbrakes sticking, then seek out a professional, such as one from Your Mechanic, to help you.