Trouble with my gauges and headlights

[Lost Sheep68]

So I have a 1968 Charger with rally dash gauges work until I turn the headlight switch on.....I get headlights but my gauges go dark and all the needles drop to zero as if the car is off......any ideas?

[b5blue]

Look at the 5V dash dodad on the back of the cluster. Lights on turns on dash lights. 

[Kern Dog]

It isn't the voltage limiter. That reduces voltage to the temperature, oil pressure and gas gauges, not the lights.
The lights are on a separate circuit and fused.
In fact, there is a wire that comes through the firewall and runs right to the ammeter, then the other side of the ammeter wire splits off in 4 directions from what the service manual calls a "welded splice.
 1 feeds the fuse panel, 1 feeds the ignition switch, 1 feeds the light switch and the 4th goes back through the bulkhead to the starter relay.
There could be a bit of corrosion in that welded splice but my guess would be a faulty headlight switch.

[Lost Sheep68]

Thanks for steering me in the right direction.....will let you guys know what the results are lol

[b5blue]

Kern is NOT an electrical minded person. If dash lights on energize ground, poof goes 5volt dodad output. But hey he has a welder.

[Kern Dog]

I not only have a welder, I also have enough sense to know what I don't know. Stick to what YOU know...transgender issues, vegan recipes and interior decorating.
I just went through some dash gauge issues last week. I was also told by well meaning people that the voltage limiter was my problem.
It wasn't.
I have had the dashes apart in a few cars and do know how they are wired. I sure don't know everything. I'm willing to learn and if I'm wrong, I have np problem admitting it.

[b5blue]

Check the screws that hold the cluster in place, they supply ground. Do what I do and just skip over Kern's moronic posts. (I stopped reading them about a month ago yet he sill yaps away.  )

[John_Kunkel]

FWIW, the IVR is powered by a pin in the instrument cluster connector.