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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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I recently was working on a 77 280z turn signal switch. As a by product I developed a headlight issues that sounds much like what your experiencing. I found that if the black ground wire running between (connecting) the turn signal switch and the headlight switch was not connected then the headlights would not come on. Driving/marker lights all worked but no headlights. Once reconnected all worked. Check that this wire is connected on your setup. It's the unmarked wire on the far right in the headlight combo switch diagram above.i

I believe this wire completes the circuit to run the headlights through the high/low beam switch.

 

As for power in your ground wire, that make sense as power ultimately starts at the + battery and needs to return to the - battery, effectively a circle. So as the power runs it's route it will show power along the way unless the circuit is broken/open (such as a switch).

Edited by 1970 240z

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I just double checked, and that unmarked black/ground between the headlight and turn signal switches is connected.

 

My turn signals don't work currently either, though the hazards do flash them properly (even with LEDs swapped out up front).

 

New flasher units are cheap, should I start there? Is there a reliable aftermarket flasher unit that will play nice with LED bulbs without the need for load resistors?

 

I also realize now that I should have disassembled and cleaned the hazard switch while the console was out of the car, is that worth doing now? I've read it can interfere with the turn signals if it's worn, even while the hazard function still works.

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There is a way to by pass the Hazard switch with 1 jumper wire. I'll post how to do this once I review which 2 wires are involved. I've done this a couple of times when trouble shooting the Hazard switch.

 

Also, (I'm sure you've done this) flick your headlights high to low and back afew times. I've seen where these old switches can get stuck in between modes and no headlights light.

Edited by 1970 240z
fixed some typos

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Thanks, saw those flashers on Rock Auto but O'Reilly also claims to stock several that are compatible so I'll stop by there today and pick a couple up. They're so cheap that even if they don't work it's nbd.

 

edit: replaced both stock flashers with this one from O-Reilly, no change in behavior. Hazards still work, turn signals (and headlights) still don't.

Edited by bawfuls

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For a 1977 280z:
To bypass the Hazard switch to allow you turn signals to work, Jumper (on the harness side) the Green wire to the Green/yellow wire. If your turn signals work after applying the jumper then you know the Hazard Switch is an issue and not working, it likely will need to be rebuilt or replaced. Usually the contacts inside the switch are dirty and need to be cleaned.

 

280z Haz bypass.JPG

Edited by 1970 240z
corrected spelling errors

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Thanks for that diagram, worked like a charm! Both turn signals worked just fine with that jumper (even blinked at an appropriate speed with LEDs up front, thanks to the new flasher).

 

Now I will look for hazard switch rebuilding guides/replacements. edit: opened up the switch, cleaned the contacts off, put it back together, and signals now work even with the hazard switch installed.

 

Just need to get to the bottom of the headlight issue now...

Edited by bawfuls

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Excellent on getting the turn signals working!
Now on to your headlights. Here is a basic troubleshoots guide I put together for someone else, I believe you have done much of this but take a moment to review it to see if anything in it helps.

Here’s a sorta step by step process for checking.

1) Start by checking the Engine bay main fusible links connections. The one closest to the fender (outer) and the front (away from the firewall) is the one that provides power to the headlight switch. These often get tarnished or corroded at the Blade connectors. Once these are cleaned and you’ve verified power on each side of the connection then move to the column.

2) Check the large White/red wire at the column; this is power from the main fusible links. This is where power enters your switch. When the switch is turned on, power exits the switch to the fuse box by way of the large Red wire with the bullet connection. At the fuse box the power is split into 2 circuits, one for each headlight.

3) Check for power at the two headlight fuses and ensure the fuses to the fuse-box connections are clean and good.

4) Since both headlights are affected, it’s not likely that these two separate power-circuits to the headlight bulbs are the issue.

5) The headlights share two common ground circuits, one for Low beam & one for High beam. Since both high & low beams are affected it is not likely these individual ground circuits from headlights back to the Turn Signal switch (High/Low selector).

6) There is a wire at the column that connects the Turn signal switch (High/Low selector) to the Headlight combo switch. Check that connection; this is where the ground circuit routes to the Head Light switch, which then continues out the large Black wire with the Blade connector to ground.

There is no factory relay in the headlight circuit. There are aftermarket kits or people modify to add a relay. If yours has this mod. then the wiring and relay for this could be a suspect as well.

Edited by 1970 240z
Corrected text shown in red-previously stated closest to firewall
  • Like 1

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-verified power at fusible links

-large white/redstripe wire at the column that goes into the combination switch does NOT have power, but when I plug it in anyway, I get 10V at each of the headlight fuses if the combo switch is in the high beam setting. No power at the headlight fuses when combo switch is off or set to low beams. This... shouldn't be possible without power at the white/red, no?

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The fuse box "headlight" circuit (see diagram earlier in posts) has a White/black wire feeding to it from the Ignition relay & Fuel Injection so power could be coming from this circuit and back feeding back up to your switch if your key is "On". The High Beam position is likely providing a grounding route, the Low Beam position may have tarnished contacts and may not be completing the ground. I think we should focus on getting power to your large White/red stripe wire at the column. There is a 6 wire connector at the passenger foot area against the firewall. It is likely behind the plastic mount for the Dash harness connections, its possible this connection is dirty.

2069780113_280z6-wireconnection.JPG.fe98b96f807978de0b4fe6cd54e21f9f.JPG

280z 6-wire connection.JPG

Edited by 1970 240z

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I got sick right before the holiday and then the usual obligations took my time, so I'm just getting back to this today.

 

Unfortunately some complications from my EV conversion have now impacted the headlight issue. Long story short, I left the 12V battery connected over the long break and it drained (because I did not have the DC-DC converter powered on to keep the 12V battery topped up from the high voltage system while I was away). The 12V battery now reads ~350 mV directly across it's terminals. It seems to me that it should not be able to discharge that deeply, but I presume it is now dead and will need to be replaced. 

 

The fact that it drained so completely while I was gone also indicates that there is some kind of leak path in the 12V system which I'll need to track down once I've got a fresh battery installed. Maybe this is also the cause of the headlight issue?

 

Not sure that I've articulated it in this thread, but I am converting this Z to fully electric drive, so I have removed extensive systems from the car. In addition to all the obvious (engine, fuel lines, fuel tank, radiator, alternator, etc) I also cut out all the EFI wiring and the ECU. I was careful to make sure that the wiring I removed was only the EFI and ECU system based on the car's wiring diagram, but still that could have introduced complications to the 12V wiring system.

Edited by bawfuls

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Finally back in the shop with some time to look at this issue again, and it feels like I'm going in circles. I replaced the 12V battery with a fresh one and started the process again.

 

-I've got power at the white/red stripe going into the combo switch on the column now (I checked the connection behind that white plastic harness in the passenger foot-well area as well, it didn't work at first but did after cleaning the contacts a bit)

-I've got 12V at each of the two headlight fuses on the fuse box, but ONLY when combo switch is on high beams, not when it's off or set to low beams

-ground connection between combo and turn signal switches is intact and reads within 1mV of chassis ground

-no power at any of the 3 headlight contacts, unless the switch is on high beams, in which case i get 12V at all three

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On 12/16/2018 at 1:17 PM, 1970 240z said:

You can bypass the High/Low switch to confirm the headlight circuit is working properly.

 

280z High-Low beam switch test.JPG

Lets try removing the Turn Switch out of the equation;

1) unplug the 6-wire connector from the switch but leave the Black Ground wire running between the two in tack.

Did this remove the "extra" power from the Headlight plug?

2) With the Headlights off ground the Red/black wire on the harness side (see diagram above for location).

3) Turn the Headlight Switch to the "on" position, do you have Low Beam lights?

4) If so, then the Turn Signal switch is suspect and likely needs to be opened up and have the contacts cleaned.

 

Edited by 1970 240z

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-unplugging the 6-wire connector for the turn signal switch did not remove the "extra" power from the headlight plug

-grounding the red/black wire on the harness side did not enable low beams in the "on" position

-grounding the red/white wire on the harness side DID enable lights in the "high beam" position, but when I unplugged a headlight to check the voltage, it's only getting 10V on the high connection. My stock lights come on with this (not super bright), but the new LED lights don't of course because they need 12V

 

As best I can tell, this is how the lights behaved when I first got the car and had it running (limping) on the stock engine. Headlights did not come on in the low beam position, came on but weren't very bright in the high beam position. That makes me feel a little better about having not fucked things up more when I ripped the engine out.

 

So this means... there's some issue with the ground loop connections? Not sure how to diagnose further.

 

Edited by bawfuls

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