I have purchased and installed a trailer light hookup on my 05 Mo with the standard 4 wire set. Now I have a trailer that has brakes and need to have a 5 wire set, so when I go in reverse it releases the brake on the trailer and allows for backup. Does anyone know if there is such a thing, because the local parts guy has no clue..??? All he can tell me is that I need a special cable for the Mo... Well I have one and its 4 wire....Help please