Lb7 started blowing ignition fuse.would either start and blow fuse wich puts trans into limp or will blow after i shut truck off and try to start again.i replaced ignition switch with no results does the same thing .sometimes i can get a couple starts but within the day i have to replace fuse.also the whole cluster either works or does not .took it in to rebuild and builder says the central unit is shot.any advise or readable diagrams would help