1955 wiring problems

[55pickupman]

I have floor mounted dimmer switch. Trying to connect the Hi beam indicator light simple I know. But I get Low voltage from the terminal on the other side. High beam has high voltage while at the same time I get low voltage on the other side. I have a simple wiring system with no relays. Does anyone know how I can eliminate the bleed over or do I need to install a diode?

Also my buddy has the 2nd series 55 pickup when you apply the brake the left front parking light comes on. Cannot seems to locate where someone crossed a wire. any ideas on where to check would be helpful.