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Discussion Starter · #1 ·
I have searched this subject and it seems most of the time it is a ground. My outer drivers side headlight is dimmer than the rest, It is a Wagner the same as my other outer and the two inners are T3's. Both grounds hook to the same place on the core support. I unhooked both grounds and the inner light got very dim, soon as I touched the ground wire to the core support lit right back up, outer one stays the same regardless if grounded or not, dim. The wiring is basically new on the car so it is not corroded or rusted.


To be honest I bought this car in June right after it had a frame off restoration and have no driven it night, so kind of ashamed to say I don't know if it has been like this or just happened. I know I turned on the light to make sure everything worked and I don't remember it being this dim..


Could it be a bad bulb or where else should look??
 

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I have searched this subject and it seems most of the time it is a ground. My outer drivers side headlight is dimmer than the rest, It is a Wagner the same as my other outer and the two inners are T3's. Both grounds hook to the same place on the core support. I unhooked both grounds and the inner light got very dim, soon as I touched the ground wire to the core support lit right back up, outer one stays the same regardless if grounded or not, dim. The wiring is basically new on the car so it is not corroded or rusted.


To be honest I bought this car in June right after it had a frame off restoration and have no driven it night, so kind of ashamed to say I don't know if it has been like this or just happened. I know I turned on the light to make sure everything worked and I don't remember it being this dim..


Could it be a bad bulb or where else should look??
It sounds likely that at least one of plugs going to one of the head lights has the wires crossed side to side where they go into the plug. I've seen this problem before, easily solved.

If you built the new plugs for the head lights then this is the most likely problem. Check the bright side against the dim side and see if they are wired the same or not.

The bulbs are polarity sensitive or so it would seem.
 

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Clean grounds and check voltages. I run my headlights off of relays. Best $20 I've ever spent. (along with cleaning all grounds and making sure you have good wiring, especially from the battery to horn relay bus bar. Having relays avoids the current having to travel through the headlight switch and back to the headlights.

A side benefit is your dash lights 'might' be brighter. (another story)
 

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Discussion Starter · #7 · (Edited)
the prongs on the headlights and connectors are both practically new and look spotless, so I don't think there is corrosion. I have a multi-meter but no real clue how to use it LOL! How would I set it up to check voltage?

Going to go out now and see if both sides are wired the same


Here is how they are wired


Drivers side outer headlight
top prong- 2 tan wires
left(drivers prong) -1 ground
Right (pass prong)-1 green


Passenger side outer headlight
top prong- 1 tan
left (drivers prong) 1-ground
right (pass prong)- 2 green
 

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I have a multi-meter but no real clue how to use it LOL! How would I set it up to check voltage ?
Post a clear picture of the meter or a link to what it is. Most are basic but you just have to have things set right on the meter for what you are wanting to do with it.

Jim
 

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here it is...
On your meter, leave the black test lead in the "Com" (common) like it is now as well as the red test lead in the right bottom hole marked "V" for volts.

Now twist the center dial counter clockwise to where the pointer is pointing at the 20V under the group of spots marked DCV (Direct Current Volts).

Now put the black test lead on the battery ground post and the red test lead on the battery positive post and the meter should then read a number in the display up on the top center of the meter. This might be a number like 12.2, or some other number but if it reads 12.2, then this means across those two points where the test leads are at the meter is measuring 12.2 volts DC.

You can then leave the black lead on the battery negative post and now with the headlights on, start probing around on the headlights and you can see where you have voltage and where you do not, or by measuring at different points be able to see if there is a voltage difference between something like one sides low beam headlight and the other sides low beam headlight. Do not be concerned if one side reads let's say 12.4 and the other reads 12.1 but if one is really off compared to the other, then there is concern. A point of concern would be is if one side reads 12.3 and the other side reads 6.0

Once you are done with the meter, rotate the center knob to the OFF position so the internal battery does not drain down. And who knows, there may not be a battery in it and if not, or if it's an old battery, put in a fresh one.

Jim
 

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since you said the wiring is new, check that the terminals are crimped on good on the dim light. you may have crimped some insulation into the terminal and are only getting minimal contact surface.
 

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Discussion Starter · #15 ·
This evening I will swap lights and see what happens, if no change I will check voltage and connections.

Correct me if I am wrong but being that only one light out of four is misbehaving it pretty much has to be isolated to that light?? I don't think I have a major wiring issue that goes far outside that one light socket or bulb.
 

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This evening I will swap lights and see what happens, if no change I will check voltage and connections.

Correct me if I am wrong but being that only one light out of four is misbehaving it pretty much has to be isolated to that light?? I don't think I have a major wiring issue that goes far outside that one light socket or bulb.
With you saying, being that only one light out of four is misbehaving it pretty much has to be isolated to that light, could be right or it might not be.

I've been installing car audio since the late 70's and I've installed plenty of radio's with 4 speakers and once in a while get one back with one speaker acting up and most of the time it is a bad speaker BUT I have had some that the radio has had a bad channel, or a wire to that speaker is shorted or broken, or a terminal not connected well, and so on but if you just go through a logical progression troubleshooting things, the issue(s) will be found.

Just like in your situation, you or I would swap the bulbs first but I've also done that only to have both lights start working as they should as it was a connection issue and you just never know until you try things.

Jim
 

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Discussion Starter · #18 ·
BAD BULB! an easy fix:)


the two non-T3 headlights are Wagner and it looks like none of my local parts strores carry em. Would like them to match so I guess I will need to order em. Car has two T3 for the high beams but they don't appear to be available anymore.

Thanks so much for all the input an assistance guys.

One more wiring gremlin and I should be good...high beam indicator does not work.
 

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Nice going Pat. I received this years ago on this forum and it's helped me out a BUNCH. Print it off in color and laminate it!
 

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BAD BULB! an easy fix:)


the two non-T3 headlights are Wagner and it looks like none of my local parts strores carry em. Would like them to match so I guess I will need to order em. Car has two T3 for the high beams but they don't appear to be available anymore.

Thanks so much for all the input an assistance guys.

One more wiring gremlin and I should be good...high beam indicator does not work.
I'm glad it was a simple fix.

Did you understand my reply about the meter ?.

On my 68 Chevy II Nova, I only have the dual headlights and bought some reproduction T3's for it and have been very happy with them. I wonder if anyone does make the quad headlights in a T3 design and if you can buy them in a broken set or individually. I know on some bench tests between some original T3's I bought, some Wagner halogen's and the reproductions, the reproductions were the brightest of the group. The original's were the worst of the bunch BUT who knows how long they were in use before I got them.

You have to wonder now if the high beam indicator is as simple as a bad bulb.

Jim
 
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