Yeah, the "control unit" is some type of module. Not sure of it's complete purpose. I'll look into things this weekend, just too wore out when I get home. If the seat switch does work, I think tying it into the solenoid wire would stop any 'self-starting' issues.
I want to see where the A & B is going to at the moment. According to that diagram, I am unsure which wire is power to the switch, may be X.