Have a 65 coupe 289 with Tremec 5 speed. Just replaced the under dash wire harness. Everything works as it should except my backup lights don't work when I go into reverse but come on when the under dash courtesy lights come on (open either door or select them by rotating headlight switch). Any thoughts or suggestions? Thanks.

 

Were the back-up lights an option in 65? I know they weren't standard so the harness you put on may not have them fed correctly. The lights should be fed through the back-up switch, top top fuse and through the ignition switch. Make sure the splice into the positive feed in your harness is before the fuse box. See attached snip. (the path is marked in orange)