I am out of ideas. My GT oil pressure gauge has not been right since I built the car. I am on my third set of senders and gauges. The wires have been checked from one end to the other. It all seems to work backwards, gauge goes negative with pressure. Tonight I pulled a known good sender and gauge and hooked them up without a car. Put pressure to the sender and the gauge goes minus. I tried different ways of wiring it and it either works backwards or not at all. Any ideas at all would be helpful. Electronics is my specialty and it makes no sense to me.