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bawfuls

LED external lights and associated electrical issues (1977 280Z)

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748773019_77-Marker-Headlights.JPG.6ad1066991ff696c7def91ae79656f4a.JPG

Hope this helps (1977 280z):
Here I've added the headlight circuit From the Fusible link into the Combo switch wire (Wht/Red) , then From the combo switch to the Fuse box (Red), then From the fuse box to the headlights.
Common issue is bad/dirty connections at the Fusible links if your not getting power on the White/Red wire at the combo switch plug. As said earlier, the Key switch is not required to be on for power to be at the headlight circuit.

 

 

Edited by 1970 240z
Removed duplicate image

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Alright so the new combo switch is here which should make testing easier.

 

I checked without the switch connected and I've got 12V at #2 and #4 (at the steering column).

 

I am also seeing the tail lights come on when the battery is connected but the combo switch is in the OFF position (wtf?). This is the case even with the combo switch completely disconnected.

 

With the new switch connected and turned on, the marker lights come on but the headlights do not, same as before.

Edited by bawfuls

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#4 should  be getting it's power from #4b,  which in turn gets power from #3 by going through the switch. If your getting power at #4 when it's disconnected from #4b, then pull you headlight fuses, you may be getting a back feed of power through the fuses.

 

also, Check the round connectors where the main harness connects to each headlight harness. Pull apart the connector, clean and test for power. These connectors can get dirty.

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Resurrecting this thread as I've come back to the issue again after 6 weeks of other things. So I have verified power at fusible links, fuse box, 4B, etc.

 

I checked power at the headlight connectors themselves, and found something weird: with the light switch on, all 3 contacts at the lights read 12V, even the one that should be ground. Tracing things back on the wiring diagram, I found 12V at the Earth connection on the combo switch. That's E on the combo switch table in the above images. When the switch is in the OFF position, this connection reads no voltage, but when on the second (high beams) position it reads the same 12V as 4B. It still reads no voltage when in the first on (low beams) position, BUT in this position the ground connector at the headlight reads 12V

 

This.... means my combo switch is wired incorrectly or shorting something? I can't find any difference in the ground connections between my refurbished and my old combo switches. (The old one did work intermittently ~7 months ago).

 

What other sources could be causing this ground to see 12V when the light switch is on?

 

I am extremely confused now.

Edited by bawfuls

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