Grigg, this a 1990 truck, so modern for me. I will use your info in the very near future to square away my 52.
What I am trying to do is use a 7 pin connector on both the truck and trailer to connect 4 wires on the truck to 4 wires on the trailer. I am doing this because I always manage to break the 4 wire flat connectors about the time it gets below zero. I have used the standard pattern of what function goes where on the connectors and taken the different color wires between 4 and 7 wire into consideration as well. So I am sure a 4 wire function is on the pin as a 7 wire function would be. I have the white wire pin on each side of the connections grounded to the frames of both the truck and trailer. I wanted both truck and trailer to have grounds as well as just the ball to hitch connection. I made sure the function pins are aligned on both connectors, by plugging them together and then sliding the housings off the wire connections so I can see both sides of the connection.
I will check the connections again, but the grounding comment may be the issue. The original trailer running lights grounded through the mounting screws and had just a power line going to the light. I replaced several of these with a two wire fixture and grounded to the trailer frame.
I can get brake and turns to work when the lights are off, but when I turn them on the trailer running lights don't work and both lights flash when I use the right turn signal. I am going to relook this again today or tomorrow, had to walk away for mental health reasons.
