1977 Auto-Dim headlight switch question

[TonyC]

Dittos Dan's answer; when turned completely off, they resort to old-fashioned manual control. Just make sure the two auto features are completely off. If my guess is right, they should both click off past a detent built into them.

---Tony

[John Mc]

I sent John a Xmas present and a surprise.

Yes you did! And I am most grateful!

[John Mc]

I ended up going to the sentinel vacuum box in the left kick panel and put together the vacuum tube that feeds the box with the tube from the box to the headlight switch. Now my headlight doors go down when the headlight switch if off. All is good.

[John Mc]

Couldn't you just take the switched power out source from the headlight switch and hook it to the trigger side of a 4 terminal relay? Run a 12v feed from the battery to the power feed of the relay? Hook the switched terminal of the relay to a 3 terminal dimmer switch? Hook the low/high beams to the dimmer switch?

If you had a Power Probe this would be extremely easy to pull off IMO.

Interesting since I will never use the auto dim system. Can you provide a little more detail or a schematic? I’m no electrical engineer.
I will mention that when I first picked up this car, the headlights worked once. Would that point to a failed relay? I checked out the headlight switch yesterday and it checked out as fine. I DO have power coming out of the headlight switch (red/yellow wire). I’m very puzzled here, any tips are appreciated.

[1Bad55Chevy]

I can draw this up for you this weekend on power point but I do have some questions about your issue.

In your light circuit does anything work when you turn the headlight switch on? Headlights, low or high, dash lights, parking lights, etc?

Have you checked the main power wire coming into the switch? Based on the schematic Dan posted it would be the yellow wire marked "Y"?

Do you own any diagnostic tools for basic electrical work? Volt meter, test light, power probe (thats a tech level tool so I would assume you wouldn't have this).

Let's start here. I know we can get this working either by bypassing it or fixing it.

[John Mc]

I can draw this up for you this weekend on power point but I do have some questions about your issue.

That would be great, thank you!

In your light circuit does anything work when you turn the headlight switch on? Headlights, low or high, dash lights, parking lights, etc?

Yes, I have parking lights, but no low or high beams.

Have you checked the main power wire coming into the switch? Based on the schematic Dan posted it would be the yellow wire marked "Y"?

Yes, I have power feeding the switch and out going (red/yellow wire)

Do you own any diagnostic tools for basic electrical work? Volt meter, test light, power probe (thats a tech level tool so I would assume you wouldn't have this).

Yep, I have all the basics for testing.

Let's start here. I know we can get this working either by bypassing it or fixing it.

Thanks in advance.

[John Mc]

Let me also note that when the headlight switch is pulled out, I have power at the dimmer relay on the red/yellow wire, the blue and gray wires and the green wires. Interesting to note that when I turn the lights off there remains a tiny bit of current on each or those wires showing on my test light. Normal?

[John Mc]

Headlight issue fixed………………..ALL 4 bulbs were burned out!!!!

Unbelievable!! Thanks guys for all the help!

[Lee]

Makes me wonder if your alternator is over-voltage.

[Dan Szwarc]

Headlight issue fixed………………..ALL 4 bulbs were burned out!!!!

Unbelievable!! Thanks guys for all the help!

Well, there's a lottery ticket few people win on.

[1Bad55Chevy]

Headlight issue fixed………………..ALL 4 bulbs were burned out!!!!

Unbelievable!! Thanks guys for all the help!

Thats was going to be the first thing I was going to recommend to check today with a jumper wire. You should really look into a PowerProbe if your going to work on old cars, it really speeds things up when your trying to diagnose stuff.

[Lee]

Chevy, I don’t really have a current need, but would you recommend one of their models in particular for general old car troubleshooting? It looks like they have quite an array of models.

[1Bad55Chevy]

Chevy, I don’t really have a current need, but would you recommend one of their models in particular for general old car troubleshooting? It looks like they have quite an array of models.

Just the basic kit. I have the PP2 kit and their short detector (I almost never use the short detector) this is the newest version of what I use
https://www.powerprobe.com/na/en/PP3LS01

The wire piercing attachments are worth their weight in gold! The benefit of this tool is you can energize the circuit (or add a ground) with the push of a button making it extremely simple to test components. I want to add the amp/PWM testing attachment to my tool box in 2024 but I honestly don't know how often I will truly use it.
Amp tester
https://www.powerprobe.com/na/en/new-product-PPAMP
And the PWM tester
https://www.powerprobe.com/na/en/NEW-PPPWM

[John Mc]

Makes me wonder if your alternator is over-voltage.

Could be overcharging, once I get my carb back and get it running, I will check the alternator out. Thank you again for all the insights.

[Lee]

Chevy, I don’t really have a current need, but would you recommend one of their models in particular for general old car troubleshooting? It looks like they have quite an array of models.

Just the basic kit. I have the PP2 kit and their short detector (I almost never use the short detector) this is the newest version of what I use
https://www.powerprobe.com/na/en/PP3LS01

The wire piercing attachments are worth their weight in gold! The benefit of this tool is you can energize the circuit (or add a ground) with the push of a button making it extremely simple to test components. I want to add the amp/PWM testing attachment to my tool box in 2024 but I honestly don't know how often I will truly use it.
Amp tester
https://www.powerprobe.com/na/en/new-product-PPAMP
And the PWM tester
https://www.powerprobe.com/na/en/NEW-PPPWM

I like it. You can almost tell it was designed by somebody who knows first-hand what you're most likely to need when you're chasing down an electrical problem.