Is there any way you could hook up a car horn or some audio device to the brake wire temporary? Connected to the electro-magnet wire on the brake you know is locking? That way you could leave the truck running with the e-brake on and wheels chocked, then you could do what the old ford eecIV manusl used to have us do which I think they called a "wiggle test", moving all switches or wires you think might be the problem, when the horn honk's even for 1/4 second it was getting power and is probably where the problem is! Just a thought Bob in Heavy Equipment Tech Full Time
