OK, now that someone has admitted to actually reading the manual, we need to go back to the OP and look at the description of his particular problem. He indicates his seat turns off after a few miles. So unless he is moving really really slow, I'm going to guess that his is turning off well before the one hour timeout designed into the system. He also indicates it cuts out after hitting a bump. Since he doesn't mention blowing any fuses, I'd guess we are dealing with an intermittent open circuit. The trick will be for him to find a competent shop with a good electrical tech who actually understands how the seat is supposed to work and who actually wants to find and fix the problem. It sounds like he has already found one of the other kind, the ones who are always looking for excuses to not do any work. You all know the type, they are the ones who always claim everything is normal and that "they all do that" before ever performing any real diagnostics or really listening to the customers description of the problem.
Jerry