1970 headlight swith, etc.

[70MTRoadster]

Hey folks, I've been driving my 70 for years with no issues with the lights. I did install kit long ago that keeps power from running through your headlight switch thus heating it up and uses relays for the lights. A fellow motorist told me my left turn rear tail light was not working.

In checking it out I found it, sort of, and other problems. With the key ON I have left front, right front, right rear turn signals. If I cup my hands over the left rear tail turn I can barely see it flicker so it is "working sort of". No wonder he said something about it. So there is that problem. The next one is perplexing...I have NO headlights! engine running or not but with key ON with the engine off. I DO have all other lights working with the headlight switch all the way OUT or all the way IN, but all lights, sans the headlights go off with the headlight switch in the MIDDLE position. Whoa!

Bad headlight switch for the lights and bad turn signal switch for the turns, thoughts??

Scott

[Habitat.pat]

Scott, check the ground on your left rear turn signal light. I’m not familiar with the headlight wiring on the high windshield cars, especially one with the relays added.

Peace,
Pat

[Bwk2000]

Could be that, but I would first recheck each ground and all connections to the headlight & turn signal switches, and then at the headlights and at turn signal light - That costs you nothing.

[redroadster]

How's the fuse box... melted ? It was a known trouble spot
Add a redundant ground to the lites see if it changes ,to rule out pos side wiring A Direct current flows neg to the pos terminal
Do a voltage drop.tests

[Curtis]

There are two ground connections on the 70 for the wiring. One in the engine bay to the frame and one to the frame at the rear. If one aide of the tail lights is working then the other light is suspect.

You cannot add a ground to the headlights because of the way they are wired. All headlight power comes from the fuse box, see drawing. The ground occurs via the headlight switch. The ground connection to the frame in the engine bay is also the ground for all other front lights and dash grounds.

If you want to go to the trouble you can set up a relay to move the power out of the switch. It would be kind of a pita. People have used the victoria british harness successfully.

https://kendo-usa.org/datsun/datsun_hea ... _69_70.pdf

[Jimmers74]

On a similar note, I added the Victoria British TR6 headlight relay harness, but may have gone a bridge too far, and added a new, plug in, headlight relay at the same time. Wired as per the diagrams, I could not get the headlights on. Snooping around with my test light on the factory 6 lead plug to the old headlight relay, I discovered voltage on the opposite side of the plug. (From the upper row to the lower row on the factory wiring harness). When I changed the connectors to the other side of the plug, I now have dimmable headlights, but at both positions on the headlight switch, park and headlight, the headlights come on. If I pull the flasher switch, park and tail lights work per Hoyle. This seems to me to be a fundamental issue, but I'm pass the point of enjoying the mental gymnastics of what is going on. I'm open to suggestions from this most astute and learned crowd.

[Bwk2000]

My best guess:

Your ‘Park’ wire connection on the headlight switch is cross-wired into the ‘Headlight’ ON wire somewhere on the TR6 harness or to/from the newly added headlight relay (or wires in between them).

Trace each of those two wires back from the headlight switch until you find where they incorrectly touch (bare wires), are connect (harness/relay) or are spliced into each other.

[Curtis]

Just this last week I helped an owner through the same problem with the headlights. First position headlights on, second no headlights and everything else on. It was the wrong switch for the car. 69-70 switch is unique to the car.

Not sure with the kit in there how it might be affected.

[redroadster]

Around 1970 the light safety switch came into being
fords was problematic on trucks .it had a weight on the inside that should by g force shut the lites off
Sealed beams easily could be deadly in a wreck
glass breaks and a carb or fuel line opens up leaking fuel
Many caught fire minutes after the wreck .
Sure it's charging ? Lites are a big bite of amps

[Jimmers74]

The Victoria headlight harness connects only to the headlights (in a perfect world). When I trace the park lights, this bypasses the headlight relay in the harness (69 model year). And I can't rule out there being wires that are touching that shouldn't be. I'll put on my Dick Tracey hat, call the Green Hornet, and give it another go.