So I have a 2005 Chevy Silverado with a 4.3L. The problem started with both front brakes locking up. Let them cool and then you could drive them for a bit. Took the caliper off after breaking the bleeder valve open the releave pressure. Put a c-clamp on it and could not budge it. Disconnected the flex hose where it attaches to the rigid line and crank on c-clamp. Fluis comes out and caliper moves. disconnected the line at the ABS pump and I get fluid out of there as well. So took MC off and it was leaking into the booster. Replaced booster and MC with new parts. Same problem. So (and I've never done this) but I bought an ABS Module from pick-a-part and installed it. Same problem. Replace ABS pump. Same problem. Bought another Module and pump from a friends friend. Same problem. Took it to a brake place. They said the calipers were bad. So I replaced calipers, pads and flex hoses then had Brake Check pressure bleed the whole system. SAME PROBLEM!!!!! So I called the brake place and asked them what they thought. He asked if I had the ABS Module reprogrammed after I installed it. NOPE! Called a place today to ask how much, $300 and they won't do it unless it's a new one. I don't mind spending the money but I am not sure that it will fix this. Any thoughts PLEASE.