Driving down the road the other day the brakes begin to lock up on the beast until they were so tight that the 8.1 engine would not move it.
All four wheels were locked and it wouldn't move till she called me and I had to open a bleeder valve on both the front and the back. One GMC forum said they had had this problem with a defective master cylinder. Parts store says no way. Only thing it can be is the hydroboost.
I replaced the master cylinder and solved the problem.
The only time this has ever happened to me was with a 71 Fiat roadster. In freezing weather the brakes locked. That was because it had too much water in the brake fluid and froze.
All four wheels were locked and it wouldn't move till she called me and I had to open a bleeder valve on both the front and the back. One GMC forum said they had had this problem with a defective master cylinder. Parts store says no way. Only thing it can be is the hydroboost.
I replaced the master cylinder and solved the problem.
The only time this has ever happened to me was with a 71 Fiat roadster. In freezing weather the brakes locked. That was because it had too much water in the brake fluid and froze.