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Discussion Starter #1
With my Nuovo Super headlights on, I noticed the driver’s side inner beam was dimly lit while the right side inner was off, as it should be. When switched to high beams, everything works properly. Both outer lowbeam headlights work properly.
What would cause voltage to bleed over to one of the high beams?
Grazie.
 

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Poor grounds is the first thing I'd check. Each headlight is grounded separately to the body, usually by a wire with round end fitting, to one of the sheetmetal screws that mounts the bucket to a nutplate on the body. Not a guarantee of a good ground after 45-50 years.
Andrew
 

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Agree. Classic symptoms of poor grounds.
 

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Discussion Starter #4
Thank you. I am on it.
Roads around here practically knock out my fillings so no doubt it’s shaken contacts loose.
 

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I'd first try cleaning both sides of all connectors, the mounting surface as well as maybe run a tap through the mounting hole, reassemble and see what happens.
 

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Discussion Starter #7
My wiring diagram points me to the cluster of grounds in the photograph that include the battery. I cleaned everything and have the same result.
Thinking I could figure which of the four is the offending wire, I connected only one. All the lights came on with the dim one doing it’s thing. I removed that one so had none of the grounds attached. They all came on again with the same issue.
I’ll be the first to admit I know nothing about electricity, but I didn’t think the circuits would work without grounding.
 

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Thinking I could figure which of the four is the offending wire, I connected only one. All the lights came on with the dim one doing it’s thing. I removed that one so had none of the grounds attached. They all came on again with the same issue.
If removing all combinations of wires attached to that ground point yields the same result, then I would conclude that your headlights may not be grounded there. What if you start at the offending bulb socket and trace the wire leading from it - where does it terminate?

If it goes to that same ground point that you have been working on, then perhaps the wire is broken, the lug isn't firmly crimped on, or ... Or perhaps the terminals in the socket or on the bulb are corroded.
 

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Discussion Starter #9
Thanks Jay. My intention trying one at a time was to determine if a wire was broken or badly crimped. The problem light is right below the ground lug, and is bundled with all the wires for the lights.
I’ll pull the rubber cover and see what’s happening there.
What throws me is everything working with nothing “grounded”.
 

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Grounds tend to "search" If there is alot of paint or such where you put the ground. It will reject it and you might get a dim light. Use a piece of wire to connect to a ground on the chassis in a known bare metal location.. Usually the NEG battery post or wear it is bolted to the body is pretty safe bet.The ground wire might have a connector that is corroded at the crimp of the wire too.. Soak it in a solution of vinegar salt and lemon juice ...like 10 to 1 tsp to 1 ratios and rinse with water after about half hour of soaking. You can soak the socket the same way evne if it is bakelite or some other manmade insulator
 

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Discussion Starter #12
The only time it doesn’t “bleed over” was disconnecting the ground wire from the light socket itself. I plan on working back from there, but it’s started to rain and the light in my garage is not good.
Tried contact cleaner, but perhaps the salad dressing of vinegar, salt and lemon juice might work. They were never as good as Crosby Stills and Nash though.
 

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Discussion Starter #13
Did the salty acid bath to clean the contacts and got the same dim glow. Spliced a new ground after the connection to the harness and got the same glow. Wired a new ground from the socket to the neg battery terminal eliminating the existing wire-same glow.
To my thinking, that puts the problem at the socket itself.
???
 

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Dim lights can be a supply-side problem too, not just a ground problem.
Got a multimeter to measure the volts reaching the light socket?
 

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Discussion Starter #16
Thank you both.
I will try both suggestions tomorrow. I do like the idea of using the “known good” process, but I had no idea that the bulb could be the issue. It is in there very snuggly.
I have a multimeter, so that’s doable too.
 

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Perhaps we need to start from square 1.. There are four headlights.. two pair....According to the owners manual, how do they operate? I ASSUME the outers have two filaments ---low beam and high beam controlled by the twist of the stalk switch.. one click parking ..two clicks low beam...then levered down for high beam.BOTH filaments on the outers are lit.. When are the inner pair supposed to be illuminated? I assume they are ONLY high beam one filament and are only lit when the outer high beams are selected high on the inner and high/low on the outer.... Do they go to a relay? Could you post a photo of your wiring diagram from the owner's manual.
 

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Discussion Starter #18
The lights operate as you describe with the inners coming on in the second position of the switch.
Here are pictures of two diagrams, one an Italian owner’s manual and the other I presume to be a Papajam version that came with the car.
If there is anything different about what I can now see, it’s that I have two green/black wires going to the connector for the light. The diagram shows one, and the right side has only hot wire.
09A880E3-5AD4-4157-ADCF-15DF1ED4CCD9.jpeg
09A880E3-5AD4-4157-ADCF-15DF1ED4CCD9.jpeg
 

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Thank you.. I'm beginning to suspect something as simple as you having the wrong bulb. The way your diagram shows, EACH of the 4 headlight bulbs is a SINGLE filament. That means when you select high beams your outer lights stay on driving low beams because there is no other high beam filament in the bulb and the inners switch to a BRIGHTER wattage and give you High beams on the inners...thus you have normal driving low beams on the outers regardless of where the stalk switch is and when you select HIGH beams the outers stay lit on low and the inners illuminate to a HIGHer wattage than the outers while all 4 are lit... Whew ..My Super from '72 has three prong dual filament H4 pole bulbs and operates and is wired differently.. Your NUOVA has been wired differently to a SINGLE pole bulb (H1) for each of the 4 headlights according to the diagram. I suspect the inners have a higher wattage that you will find in the index list on the schematic page. Now to the wiring colors.. Hot Wires: The grey/black is correct for the outer LEFT light and has it's own fuse (probably). Continuing on the left side, the inner is green/black and again probably has it's own fuse. these should be in the fuse box anywhere from 6 to 10. The right side of the car has SOLID grey for the outer and SOLID GREEN for the inner and also PROBABLY have dedicated fuses..Each one of these circuits is independent of each other and I don't see a bridge of one sharing power with another My advice would be to examine the bulbs on the side that works correctly. Use rubber latex gloves to remove the bulbs so you don't get any skin oils on the glass of the bulbs. Then compare what is on the side giving you problems.. OKP would be my go to place for bulb solutions. They offer a H1 bulb and I suspect for this specific model. They are very helpful on the phone. Hope that helps. PS The outer headlights draw their ground from of all places the side maker lights while the inners have a "gang" of 4 wires grounded probably ahead of the radiator on or around the top rail of the chassis. BTW H4's three prong light bulbs MIGHT WORK But I wouldn't be able to advise how.
 

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Discussion Starter #20
Thank you again, and here’s another twist to the story.
I found another wiring diagram inside the plastic cover with the Papajam version and I’m not sure it applies to my car. It shows the outer light (19) having two wires going to the connector (green/black and grey/black) which would apply to the two filament bulb you suggested. My car has two wires going to the inner on the left, but only one to the inner on the right. That second wire must be sending current from somewhere.
Today it’s swap right and left bulbs for starters.
 

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