Headlight Open Short Circuit?

[CherryBomb]

Hey all. I recently installed a new engine bay and headlight harness in my '66 and several things started behaving better, including the headlight closing circuit. They shut perfectly the moment I connected the battery, which they did not used to do before. Unfortunately, they do not magically open when the headlights are turned on. In fact, I now have an issue I never used to have, likely because there was no power to this circuit in the old harness.

When I turn the headlights on, they come on but the buckets stay in the closed position. The "hold open" switch has no effect on this either. The light green wire, which runs from the headlight switch into two of the relays gets hot (as in temperature) very quickly. There is also a darker green wire that connects to the upper drivers side microswitch that gets hot at the same time. I attached wiring diagram pics, and highlighted the relevant wires to save your eyes the hassle of following the spaghetti.

Some things we have tested:
- The wires get hot even when not connected to the microswitch
- Wires still get hot after disconnecting the high beam switch
- Disconnected the three prong connector under the dash that the dark green wire runs to (L24), still gets hot

I am posting this here on the off chance one of you might have some insight into the function of that wire, and what could be causing this issue. My brain keeps jumping to a short circuit, but it is not blowing a fuse, just getting hot. I am doing everything in my power not to replace the under dash harness as the price tag is astronomical.

Important notes to save you guys questions:
- Professionally rebuilt and tested working motors with clean connections
- Rebuilt microswitches, tested relevant one for continuity and it works
- New headlight motor relay kit from Headlight Motor Man
- New headlight switch
- New engine bay wiring harness and headlight harness
- New bulkhead connector, all original connections cleaned up during repinning
- Under dash harness is original
- High beam switch appears original
- Ensured the "lamps not locked" bulb was properly grounded and bulb is good
- I connected the new relays exactly how the old ones were connected, the old did not appear to have been touched in a long time

Any insight at all would be greatly appreciated. I'll continue chipping away at it on this end, if any breakthroughs happen I'll keep you posted.

 

[turbine68rt]

@Don Frelier

 

[bcOH67]

I’m no one to listen to, but I’ve been where you are haha.

Maybe disconnect the forward light harness and send 12v directly to the open and close wires to for sure eliminate possible issues up front. If you have a power probe it makes that easy. You said hold open switch doesn’t effect it- do you mean switch up or down, or did you make a jumper and connect the two wires straight together bypassing the switch. Just trying to things of ways to eliminate possible things to narrow it down. Good ground on the control relay?

I had issues for years with mine even though everything tested good. Wound up giving up and making a relay bank up front, bypassing the relays in the glove box and just used the power send from the headlight switch and sent it up to the front to activate. Hold open switch turns on my backup camera now haha. Works great and gets all the power they need.

 

[twecomm]

The schematics show a "physical" representation of the relays instead of a traditional schematic representation of each relay. Looks like it would be easy to get some of the connections confused.. If wires are physically heating up, you definitely have a problem..

 

[CherryBomb]

I’m no one to listen to, but I’ve been where you are haha.

Maybe disconnect the forward light harness and send 12v directly to the open and close wires to for sure eliminate possible issues up front. If you have a power probe it makes that easy. You said hold open switch doesn’t effect it- do you mean switch up or down, or did you make a jumper and connect the two wires straight together bypassing the switch. Just trying to things of ways to eliminate possible things to narrow it down. Good ground on the control relay?

I had issues for years with mine even though everything tested good. Wound up giving up and making a relay bank up front, bypassing the relays in the glove box and just used the power send from the headlight switch and sent it up to the front to activate. Hold open switch turns on my backup camera now haha. Works great and gets all the power they need.

I tried both positions on the switch, as well as disconnected fully, however I cannot remember if I tried a jumper bypassing the switch. Will give that a go. I like your idea of isolating and using a power probe to see what wakes up. Thank you for the ideas.

 

[CherryBomb]

The schematics show a "physical" representation of the relays instead of a traditional schematic representation of each relay. Looks like it would be easy to get some of the connections confused.. If wires are physically heating up, you definitely have a problem..

That is true, I do also have a page that shows the traditional schematic as well. Irritatingly, the wire colors on that diagram don't match the other diagrams that I posted (which also match the car) so it is a bit tricky to cross reference.

 

[bcOH67]

No problem, hope you get it figured out! Just thought maybe the switch is bad regardless of position. You could also buy a cheap switch at RadioShack or off Amazon just to test the circuit. I said check the front too because all of my limit switches checked out but found that the knob on the housing wasn’t depressing the button well. Maybe get a long jumper wire and run it directly from your battery to the control relay ground and be sure that ground is good.

 

[CherryBomb]

No problem, hope you get it figured out! Just thought maybe the switch is bad regardless of position. You could also buy a cheap switch at RadioShack or off Amazon just to test the circuit. I said check the front too because all of my limit switches checked out but found that the knob on the housing wasn’t depressing the button well. Maybe get a long jumper wire and run it directly from your battery to the control relay ground and be sure that ground is good.

Will hopefully poke around one evening this week. The car survived Helene, but work is a bit manic at the moment playing catch up.

 

[bcOH67]

Oh man, sorry you got caught in that. Glad it seems you’re doing alright though, and the car made it haha

 

[CherryBomb]

Oh man, sorry you got caught in that. Glad it seems you’re doing alright though, and the car made it haha

Definitely thankful! I appreciate it.