I have a 69 which was taken apart when I got it. Have been working on it 4 years. Cannot find out what the light in the dash wiring toward the middle of the dash goes to. It is a 1 wire plug in light, wire is black with a yellow stripe. It is the type which needs to plug into something which will ground to complete the circuit. Comes on with the park lights but goes out with the headlights. Any help appreciated.