'37 Terraplane headlight wiring.

Hudsonrules

:unsure: One more minor problem with my '37 Terraplane. The head light wirew have been cut near the radiator. no power to them. There are four wires, three look to be about 12 gauge, one 14 gauge. Okay, when I hook the small wire to the battery, low beams work. hokk two wires together, the parking lights work, lastly the last wire and one headlight works. I put a circut breaker, one end to the battery, and used theprod {tip} on each of the wires and the test light came on each time. Like each was a complete circut, I thought that the light would come on if only one wire was grounded as that would be a circut. Am I doing something wrong? or do I rewire the headlights? Thanks for any help. Arnie In Nevada.

Jon B

Have you consulted the factory wiring diagram (in the on-line shop manual on Alex Burr's website)?

There should only be three wires to each headlight: high beam, low beam and parking light.

The original wiring might have included the 14 gauge wire either for the optional fender light (which would have been on the same circuit as the parking light) or it might have been for the optional exterior horn.

There would not have been a separate ground wire, because grounding would have taken place through the headlight shell, the grille shell and the body.

I would definitely rewire the headlights if I were you, and include a separate ground wire that's soldered to each headlamp socket and then grounded to the car frame.

Marconi

O.K. I think you pickup the power to the headlight switch from either a circuit breaker or main fuse and I think it's a fuse on the 37 10 ga wire to the bat terminal on the headlight switch then one wire goes to the parking lights and the tailights and licence plate lam, check with test light to see which one's hot at the first position of the headlite switch. Whichever terminal is hot at the second position goes to the dimmer switch also a 10 ga wire the two other terminals on the dimmer switch go to both lo beams and the last one to both hi beams. The wire to the hi beam indicator on the dash goes to the same terminal as the wire to the hi beams. Use 12 ga wire from the dimmer switch to the headlamp terminal strips. If you can find one get a headlamp relay, it'll letyour headlamp switch live as then it will only be carrying current to operate the relay instead of the 15 to 20 amps for the headlamps.

[Deleted User]

Fifth Avenue Internet Garage lists 6 Volt headlight relays. I would use the 2-relay setup Jon advises, not the 1-relay setup some folks show. Where on the dash is the beam indicator located? I cannot spot it in the wiring diagram.
BN

Jay_G

Marconi mis-spoke, there is no indicator light. Well not on my 37 Hudson anyway. also remember the headlight bulb itself has two filiments that go to one ground so you can get a complete circut depending on which wire you put power to. If it were me, start fresh with new wires into each headlight bucket. Yes, it is a pain. Don't get to carried away by greatly oversizing the wires, for example if you use 10 for all the wires including a ground they will not fit through the hole. So the parking can be as large as 12 but 14 would be fine and you can get two 10 for each of the headlight curcuts and a 12 for ground. if you are using a relay for the headlight high and low use 12. I placed the relays near the terminal strip that connects the headlights together this cut down on the distance and any power loss. Then I did not have to add or cut out a lot of wire and it is close to the battery to pull power from.

Marconi

Sorry guys, I didn't realize that the 37s didn't have a hi beam indicator light, so disregard anything I said about it.