The Stovebolt Site Forums The Shop Area The Electrical Bay Dome light / Headlight switch connection question (1957 3100)

1957 3100. I am trying to sort out the dome light connections. Current socket has 2 wires attached to it. They are both black with a white tracer. It looks like they may have been spliced in. It is a 2 contact bulb and socket. Where do these wires enter the cockpit? There is a shorter gray wire with both ends hanging loose near the fuse block, with factory ends. Could this be related to the dome light? It looks like it might connect to somewhere on the fuse block on one end and the other onto the light switch. Which connector there? I have attached a photo. The instrument cluster lights (gray wire) attach to the 3 terminal side. The instrument light work. Does the rheostat (which is in marginal condition) control the dome light as well? Additionally, I have seen diagrams that show a ground wire attaches to the terminal on the opposite side of the switch from the 3 contact terminal. There was nothing there. Should I attach a ground wire there? Or does something else go there.
Sorry for the rambling. So much of this wiring has been modified over the years that I would like to get it back into some state of normalcy. Thanks in advance!

As you say, there have been many modifications to the system over the years. You have no way of knowing what's what, what's been done , and what's been done properly.

If I were you, I would start from scratch and rewire the entire truck with brand new wiring - even systems that are working now. Start with say, the headlight circuit, and work your way back. Do it by the book and it will all come out fine.

My truck had all kinds of modifications, too. The previous owner was dyslexic and got wires mixed up so headlights would only work on hi beams. There were splices and Micky Mouse connectors all over the place. He even had #3 and #4 spark plug wires reversed and he transposed characters when registering the vehicle so the title doesn't exactly match the truck ID.

Anyway, I re-did the headlights with help from this board and have been removing dead end wires and dangerous connections little by little.

I suffered a total loss fire on a vehicle from worn out wiring. It's not something you ever want to experience.

Otto, I appreciate your response. I agree, a complete harness is the way to go. I have done that on other vehicles I have owned. However, the immediate need is to try to get the dome light operational. or at least know 'which wire goes where'. Thanks again!

If using stock switch. one wire goes to "D" other goes to ground post opposite side of gauge wire. closets to the pull knob.

does not matter which wire goes where. D is the positive and ground is made when turning knob. thus completing the circuit. in theory the one to the center post of bulb socket should be 'D' if you want to be super correct.

So, if all were stock...there is an orange and a white that go up to the dome light? According to the diagram, then the white is also a ground? My dome light has 2 contacts/2 filaments. Not correct? Because it appears to be grounded through the bulb socket itself. not a wire. I am confused. And does the wire pair come out of the A pillar? Or could it go over to the fuse block just for a jumper to the switch? Still not sure where my short gray terminated wire goes, if anywhere. Thanks for your patience.

oops! I see that my 'short gray' wire should goes to the fuse block to be used for an option later? Radio light?

The bulb should be single filament.
The only wires going up the a pillar should be the two for the dome light.
Unless someone has changed the socket the two wires are just completing a circuit thru the bulb. Easy to test with a multi meter. test without the bulb then put the bulb in.
The socket should not have any contact to ground via the holder light metal.
if the socket has two posts on the inside the that is the circuit and the bulb should only be using those two posts.

orange and white or gray and white have seen both.
Does not matter as long as the two wires going up and back are the same circuit.
Yes some other post/wires are there for things like door or floor lights i am sure that came later.


DO NOT ATTACH Ground additional ground wires to the switch. The "Ground" markings are telling you that post is already connected to ground via the switch metal to body contact.

See the picture I sent you before or do a search online for 3100 1957 head light switch wiring you will will find all kinds of diagrams out there.
your comment below

"I have seen diagrams that show a ground wire attaches to the terminal on the opposite side of the switch from the 3 contact terminal"

those are not ground wires but circuit wires (yes the ground side of the circuit) but not direct to ground.

You should have one of your wires on those posts. (wire attaches to the terminal on the opposite side of the switch from the 3 contact terminal) side
The other in the middle for the switch.

to solve this problem.

"So much of this wiring has been modified over the years that I would like to get it back into some state of normalcy."

Get a good color diagram that is supposed to be for your truck. Plenty online to choose from.
Print it out. The pick a starting point and just do a validation of what is in the right place. What colors are different and what is missing.
That way you know where you stand.

OK! Thanks for the clarification about GRD. That was puzzling. Reaching behind the dash to the A Pillar I found a pair of wires molded together. Not sure if I can actually get to them. (May need someone with a younger back!) The dome light bulb/socket is an 1176. 2 filament. So it must have been changed. My first thought was a dome light/door light type of combination. But looking at the wires, it was changed to this dual wire setup somewhere in the past. With your help, this is now making a bit more sense. Replacing the dome light to the proper one, connecting the paired wires to both sides of the switch, and leaving the short gray jumper wire to be used at a later date, make this all much clearer. Now to find a younger back, with nimble fingers, to access the A Pillar wires. Thank you!!!!