I have the same configuration on my 81CJ7. 2 black wires from the proportioning valve to the firewall junction block. If I'm not mistaken, this is looped over with the red brake lamp along with the e-brake switch. I would try to go to the Painless wiring site and look for similar issues. I would look in the support section. If you don't find the answer there , e-mail their support tech. I would hate to lead you to the wrong direction by the original wiring diagram since I've had several experiences with their wiring kits that required a different wiring installation. As for the reverse lamps, the 2 wires that goes to the reverse switch is a supply and ground. Make sure there's a 12v or battery voltage coming from the supply circuit and a good ground on the other lead.