radio installation antenna causes short

I had a similar problem Friday evening. I was driving my kit car home and turned on the instrument lights, the engine lost power. It was not completely dark so I turned the switch off and all was well. I slept on the problem, because I could not think how that that could happen.

There is a secondary relay in the front since the tank and pump are up front, ECU and engine is in rear. The relay ground was tied to a spare instrument feed. I got the supply instead of the ground. The bulbs provided a good ground for relay coil, but with lights on relay turned off fuel pump. It is fixed now by using correct ground. I hope that is the only error. The wires are the same color, and the 33 year old number tags are falling off. I also have to get into a very awkward position to get under the dash.