I bought all the new wiring for my tail lights the front harness and the rear and new tail lamp assemblies, when I hook them up and test for a hot I have one hot with just my parking lights on once I install the bulbs the housing is hot all the wires going to the back are hot, there is 3 wires in one plug and then a single wire to another plug I know it must be back feeding but I'm not sure why or how. Now when I was installing the tail lamp harness one of the little tabs where it plugs up to the bulb fell off I manufactured another one and it seems ok but I don't know if maybe that was the problem, I was really disappointed it fell apart I guess I should have just sent it back. Any ideas or help is appreciated.
The harness from the firewall back to the rear cross sill will have three wires, one is green, one is brown and one is yellow. If it has a fourth wire, it will be green, for the reverse lights, that standard equipment on the fleetsides starting in 1966. This harness has a three tab rubber connector on each end. One end plugs into the hole the firewall and the other plugs into a hole in the rear cross sill. Inside the cab, at the firewall, there is a three slot female plug, that connects to the under dash harness. At the rear cross sill, there is a three slot female connector that connects to the tail light harness. I apply a liberal amount of dielectric grease to all connections and around the outside of the grommet, to allow easy insertion into the firewall and rear cross sill, as well as the connectors. A good connection is important for maximum current flow and minimum resistance, thus a brighter lamp. I recently spent a few hours troubleshooting my tail lights, only to discover that the body harness must have had some malfunctions inside the insulation, therefore a bad current, causing a dim brake and flasher. After replacing the harness, they work excellent. I wish I had replaced this harness first and saved myself a few hours time. I think the harness cost me about $20.00 and ten minutes to pull out the old one and install the new one in its place. Good luck with your project. Tony 4-5-6 Chevy Trucks
