For a many many weeks I have been installing a 20 circuit Speedway harness into my 56. I finally got to a point to start testing out my install After realizing I forgot to install the dimmer switch and fuses, most everything is working, except the wipers and the dome light. I think my wiper motor is bad since it was not working before the swap. The dome light wont turn off though. The issue is that since the harness is designed around a Chevy, its not straight forward for a Ford. My understanding is that GM does not you body grounding for a number of items including the dome light. It seems that the headlight switch cuts power on and off by terminating the ground. The Ford dome light uses body ground and it is constant. I also wired in the door switches, which work great once I removed the fuse for the dome feed. Problem is this feed is shared with the brake switch, so leaving it out is not a option. What can I do to make this work on the light switch and the door jams. Is adding a inline toggle switch my only option?


Here is how I set it up.

 

Here is how I set up the dome light, and how GM did it at least to the 1990s, very simple.
Fused 12v to one side of the dome light.
Ground side of the dome light goes to the drivers side door jam switch, jumped over to the passenger side door switch, and also jumped to the ground lug of the headlight switch (goes to ground when the headlight **** is rotated fully to the left).
Door jam switches are threaded into the door jam so when the door opens the plunger springs closed and completes the ground side of the circuit. When the door is closed the jam switch is open. If your door jam switches are bolt in style with two terminals then one terminal will need a wire tied to ground.

Excuse the crude drawing, but it works

 

The stock '56 dome light also has a switch on the light itself that powers the circuit for "manual" lighting. One side of the bulb is constantly grounded, so the OP's circuit is the only way the stock lamp will work. I don't understand why there is a problem? Is the headlight switch non-stock? Sounds like it may be GM?

 

Correct, its a GM style switch that came with the Speedway kit. The dome light does not have a switch on it. Its like this http://www.ebay.com/itm/1953-54-55-56-Ford-Truck-Dome-Lamp-Light-53-F100-F250-/141333584608?pt=Motors_Car_Truck_Parts_Accessories&hash=item20e8235ae0&vxp=mtr The light housing is the ground and there is no ground wire.

The door switches are 60's ford snap in pieces.

 

You'll have to wire in a separate switch, or figure a way to isolate the base from ground (nylon washers / bushings on mounting screws?) You can't use the headlight switch contact.

 

If he wires it the way I showed it will work with the GM switch. Just have to isolate the dome light body from ground and tie a ground wire from the dome light body to the switches and headlight switch "dome light ground" terminal.

 

This exactly how I did it in my 56. It works great no issues at all.

 

Thanks guys. This is the first time the truck has had a dome light that I know of. Im going to be a little lazy and wire in a toggle switch for the light.