Chevy 7 Pin Trailer Wiring Diagram. It reveals the parts of the circuit as simplified forms, as well as the power and also signal links between the tools. WOW, interesting - seems like a pretty obvious screw-up, I think we have a couple test-trucks parked out back.
Look at the wiring diagram for your truck and determine the designation given to the ground location for the taillights. I have a friend with a chevy truck I have found the wiring diagrams (BELOW) for the trailer. If you want to install a brake controller that's another issue wiring-wise, and there are threads here which cover that too.
It can be used to connect the taillights, brake lights, reverse lights, turn signals Unfortunately there are several ways to wire a trailer especially if it is home made.
Look at the wiring diagram for your truck and determine the designation given to the ground location for the taillights.
Don't try yellow to yellow and Note that the pin assignments are consistent with yours, but not the wire colors. Anyone have a diagram of which pins supply which functions? I found a diagram on the web (see attached), but can't tell if the diagram is from the front or rear of the connector - ie if you unplugged it at looked at the side that mates with.