# Headlight switch no power!



## Lodginghurdle (Jul 28, 2020)

Hello,
New to the forum , recently acquired a 1967 lemans that sat for 20 years. Got everything fixed up and getting road ready and I have one issue left. Some of the wiring behind the dash was chip shopped when I bought it. As well as in the engine bay. I put a new full engine wiring harness in hoping to help with my problem to no avail . None of the lights/ parking /headlights / brake lights work. I’ve determined there is no power to the headlight switch (red wire). I’ve also determined the lower 4 fuses on fuse box have no power. If I jump the fuse everything works as it should. So I’m clearly not getting power to those fuses. Now what’s got me stumped is I have stared at the wiring diagram and the power going into the switch is a red wire that connects to the back of the fuse box. What I can’t figure out is we’re the power should feed these fuses from. I’ve looked at the other wires that attach to those 4 fuses and none seem to go to ignition. Any help would be appreciated !
I assume the headlight switch should run 12v all the time. If so one would think that there should be power from the battery to the fu
Thanks


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## O52 (Jan 27, 2019)

The headlight switch does not have a fuse, but gets its power from the battery through a splice that connects the horn relay, starter, voltage regulator and alternator ((Black wire with red tracers) which also feeds the battery side of the fuse box powering up the four fuses. The wire turns red as it passes through the bulkhead (firewall) connector.

The fuse box has two sections. (Not sure about the 67 box) Remove the mounting screws and pop off the clips for the fuse section. Behind it are the terminal connections. Check the red wire for power to the fuse terminal.
If the red wire has no power at the fuse terminal, check for power at the horn relay.
If you are able to jump across the fuse and everything works then either the fuse is bad or the terminals are corroded.

Photo and descriptions are from my 68 manual and my 68 fusebox and will differ from a 67, but should give you an idea what to look for. Red wire is on the right.

And be sure to disconnect/connect the battery as required


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## Lodginghurdle (Jul 28, 2020)

Th


O52 said:


> The headlight switch does not have a fuse, but gets its power from the battery through a splice that connects the horn relay, starter, voltage regulator and alternator ((Black wire with red tracers) which also feeds the battery side of the fuse box powering up the four fuses. The wire turns red as it passes through the bulkhead (firewall) connector.
> 
> The fuse box has two sections. (Not sure about the 67 box) Remove the mounting screws and pop off the clips for the fuse section. Behind it are the terminal connections. Check the red wire for power to the fuse terminal.
> If the red wire has no power at the fuse terminal, check for power at the horn relay.
> ...


thank you 
I do have the fuse box disconnected and pulled back and there is no power to the red wire. I’ll check the horn relay for power and see if that’s my issue and circle back


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## Lodginghurdle (Jul 28, 2020)

Ok so I checked the relay this wire black with red tracer has power to it. If this is the last point before the power goes through the firewall then I assume this may be the culprit. Upon inspection there is one tab that does not have a connection on it. Right next to the black /red wire. It also tests at 12v with ignition on ( didn’t check with ignition off) my assumption is another wire should attach to this?
Thanks


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## Lodginghurdle (Jul 28, 2020)

Lodginghurdle said:


> Ok so I checked the relay this wire black with red tracer has power to it. If this is the last point before the power goes through the firewall then I assume this may be the culprit. Upon inspection there is one tab that does not have a connection on it. Right next to the black /red wire. It also tests at 12v with ignition on ( didn’t check with ignition off) my assumption is another wire should attach to this?
> Thanks
> View attachment 136296


Ok another quick update..
So after some googling looks like that 4th partial plug stays empty. I did realize when car is on while checking voltage on the light switch red wire nothing. But if I push horn button I hear clicking and I start to get some readings. There low and bounce around but while pushing the horn I get it up to 4 or 5 volts to the switch. Could this be a bad relay?
Thanks for all the help


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## O52 (Jan 27, 2019)

I did some digging around too this morning. It seems that the horn relay is an end point not a transfer point like the Chevys. 
And its starting to look like a connection problem at the bulkhead connectors. 
Since this is a battery power problem check everything with the key off. 

Remove both bulkhead plugs. Check for power on the terminal for the black with red tracer wire. It will probably be very greasy which is normal. If you have power there, check the mating terminal on the interior side for any damage. The red wire should be on the other side of this terminal. Check for continuity from this terminal to the fuse block red wire and the headlight switch red wire. If it reads zero resistance the wires should be good. 
Reattach the plugs. Make sure they are locked together and ft snugly. Tighten and check for power.


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## O52 (Jan 27, 2019)




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## Lodginghurdle (Jul 28, 2020)

Thanks Ed I will take a look. The engine side harness is new I just put it in but had the problem prior to that when I got it. Hoped fixing the rats nest under the hood would have fixed it but I guess not. I’ll run out and take a look.
Any thoughts to why pushing the horn would cause reading from the hot wire on the headlights?
Also we seems to stumble me is the wiring diagram I have shows the red wire leading straight off the switch to the fuse box . Mine looks like yours so the red is in the same position. I would think in that case something else would have to feed power to the switch.


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## Lodginghurdle (Jul 28, 2020)

Ok 
So, I do have power on the wire going into the firewall. Also on the inside of the firewall. That wire goes straight to my ignition though it doesn’t go to the fuse panel.


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## O52 (Jan 27, 2019)

Yes I saw that on the diagram. Been looking for a factory wiring diagram on the web instead of the aftermarket one.


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## O52 (Jan 27, 2019)

And I found something. It appears there's a splice in the battery circuit that connects the headlight red wire to the battery red. See photo at the bottom it shows a BAT splice


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## Lodginghurdle (Jul 28, 2020)

See that makes sense , I couldn’t figure out wire the wire would be such a heavy gauge to carry wire from a switch. It seems more related for a battery. I was debating on adding a splice and running it to the battery. It’s possible somewhere on the loom at some point this was removed. I’ve never unraveled it. I do know the main power wire going to the ignition melted (previous owner) and he cut at firewall and ignition and replaced so it’s very possible that wire has a splice at some point that would feed the fuse. It’s hard saying but it sounds like it would be safe to splice it in on the back of the fuse box . Sound like a good assumption to you .
Thanks


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## O52 (Jan 27, 2019)

Some more. 






67' GTO taillight functions explained and schematic needed - PY Online Forums - Bringing the Pontiac Hobby Together


67' GTO taillight functions explained and schematic needed 66-67 GTO Tempest & LeMans TECH



forums.maxperformanceinc.com


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## Lodginghurdle (Jul 28, 2020)

Well Ed! I think we’re going that route. I will drop a splice straight out to the battery. And since I know everything does work well once this is done I should be able to get the dash back in her so I can move closer to cruising.
Thanks a ton for all the help great info


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## O52 (Jan 27, 2019)

Took the words out of my mouth. Factory probably spliced it inside the interior to the ignition switch red wire but you can run a #12 red wire from the back of the alternator to the hdlt switch or fuse box. This will insure brighter head and dash lights. There may be a rubber grommet near the bulkhead plugs or the heater motor wiring you can run the wire through.


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## O52 (Jan 27, 2019)

And your welcome. Much better sitting inside the house today doing a little research than looking for a part I put somewhere in the garage. 👀


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