I'm having some wiring problems and was wondering if someone would be willing to email me the wiring diagram from the service-repair-manual for my truck ? Its a 1977 1 1/4 ton ex-military truck that was converted into a wrecker, now I want to use it for a plow truck. We just installed a trailer wiring harness along with a trailer brake. Now when the head lights are on I have no brake lights. Horn was re-wired to a external button, dash lights don't work, just need to sort it all out.