My 1955 Model 88 main lighting switch gives me parking + instrument light, and headlamp + instrument + tail lamp. Is this correct wiring? If not, how should I rewire the lighting switch?
The tail light should come on with the parking (pilot) light. If you look at the switch, you need the connection to the tail light coming off the same terminal as the speedo light. Some switches leave the pilot light on when the headlight is selected but this is not very good practice.
That is what I thought.
At present, the instrument lamp comes on in either position. That's what the tail lamp should do. At the moment, the tail lamp only comes on when the switch is on 'headlamp'. That's what the speedo lamp should do.
So the answer is probably to swap the tail lamp and instrument lamp leads. That should be easy
... that the speedo light would only come on with the headlight but you could probably live with that.