99 f250 brake problems
 

im workin on a 99 f250 4x4 7.3. the brakes are locking up after a short drive doesn`t happen every time i step on the brakes but almost, all four wont release the only way i`ve found to release them is bleed a caliper doesn`t matter which one i bleed it release`s all four, the truck does have abs on the rear only, no abs or brake light shows up on the dash.
not sure where to start.

Start at the master cylinder.