headlite question

[barbee6043]

I have never had any headlight s that did not work except need of replacing switch. This is a 62 Lancer. I have new and working dimmer switch. The high and low beam wires at firewall ( red , black) are hot, when I punch the dimmer for each to be hot. same thing tests tru to the headlight terminals ( where the bulb goes).I have good grounds.
I can test at the headlight terminal where the NEW bulbs is inserted and I have current at ALL the bulb prongs, even the ground. Same thing at the low bean and high beam bulbs. I unplug the bulb and test the terminal and just the wire that should be hot is hot.
This car has 4 headlights the bulbs are #5001 and 5006 was it?
What am I missing?

 

[Dana67Dart]

Some times a bad connection will flow electricity (multimeter reading) when not under load, BUT under load the voltage drop is so much that there is no flow. try to measure voltage under load and see what you get.

ALSO if you are measuring using the negative post on the battery try using a different ground (IE block or sheet metal) you may have lost battery to engine or engine to chassis ground.

I assume the rest of the car works as expected?

 

[harrisonm]

At the expense of sounding like Captain Obvious, if you have a good 12 volts (or so) of current going to a known good headlight WITH a good ground, the headlight will work. How did you test the ground? I had a similar problem when I put my 69 Barracuda back together a few years ago. It turned out that the ground wire from each headlight pigtail ran to a wire that was screwed into the firewall. That screw/eyelet combination was not making good contact. First, test the headlights with 12 volts. Then test the ground more thoroughly. Like I said, 12 volts to a properly grounded good headlight has to work.

 

[Dana67Dart]

I have current at ALL the bulb prongs, even the ground.

Reread this line and if I understand corectly...

1. When you place the negative lead of the multimeter to the negitave terminal on the battery (or a good ground) and the positive lead of the multimeter the positive side of the headlight terminal WITH the lamp inserted you get 12V
2. When you place the negative lead of the multimeter to the negitave terminal on the battery (or a good ground) and the positive lead of the multimeter the negitive side of the headlight terminal WITH the lamp inserted you get 12V

Assuming this is correct... you do not have a ground to the headlight terminal.

 

[AJ/FormS]

The outboard bulbs should be three prongs and are the hi/los
The inboard bulbs should be two prongs and hi beams only.
Therefore if the inboards do not lite but the sockets shows both power and ground then you need to pull some amps through the power wire and see if it will co-operate. The headlights require more power than what a test light or a VOM can pull. Having12 volts on both legs of the two prong bulb simply indicates that the filament is good.
You can pull the amps by powering up the bulb on either leg, and grounding the other to the battery. If the bulb now lights, you have a faulty ground. If the bulb still does not light,pull it out of the socket and power it up from the fully-charged battery; if it still does not light, throw the bulb away. But if it now lights. then you have a faulty power supply.
After you fix the supply side, and the bulb still does not light. then you still have a bad ground.
The headlight socket grounds should be tied together in the harness and a short jumper from there to the core support usually on the driver's side. Then there must be a ground return from the core support to the battery. You may be able to take a shortcut by simply jumpering the core support to the battery. If the lights now work, then just fix the ground.
Sometimes there is a ground jumper from the firewall to the passenger side head. This reroutes the ground thru the engine and out the ginormous ground cable back to the battery.This jumper is often forgotten during an engine transplant or RnR.
This is how I remember it..... good luck

 

[harrisonm]

Reread this line and if I understand corectly...

1. When you place the negative lead of the multimeter to the negitave terminal on the battery (or a good ground) and the positive lead of the multimeter the positive side of the headlight terminal WITH the lamp inserted you get 12V
2. When you place the negative lead of the multimeter to the negitave terminal on the battery (or a good ground) and the positive lead of the multimeter the negitive side of the headlight terminal WITH the lamp inserted you get 12V

Assuming this is correct... you do not have a ground to the headlight terminal.

.
I am glad you caught that. I was going to mention it, but I got distracted.
I bet it is a bad ground.

 

[Dana67Dart]

Having12 volts on both legs of the two prong bulb simply indicates that the filament is good.

one side of a 2 prong bulb should go to ground and if it was properly grounded it would show 0 volts. If it had an open ground it would show 12 volts and indicate the filament is good.


Properly working cir.
Good ground, good filament, test to + terminal of socket

Good ground, good filament, test to - terminal of socket

Open ground, good filament, test to + terminal of socket

Open ground, good filament, test to - terminal of socket

Open ground, bad filament, test to - terminal of socket

good ground, good filament, open positive, test to + terminal of socket

 

[AJ/FormS]

That may be true if the bulb is drawing full current, and shining brightly .
But say you wired the bulb with a single .007 strand of wire, choking current flow, same as if the the bulb on the car had a high resistance power connection. You would still have 12 volts on the power supply side,but the bulb would not lite, and the filament just becomes a resistor-wire. But since it cannot draw enough power to heat up, now it is just a piece of wire, so whatever voltage went into it, near same comes out.
If you try this with a regular wire it just burns up, but that filament was designed to not burn up.
Am I wrong?
If you reread Barbees post, that is exactly what is happening.

It's like a garden hose hooked up to town water that runs at 50psi. you can adjust the water flow with a walltap all you want from full on to a trickle and the pressure remains the same 50psi on the supply line.
I mean think of the starter cable. imagine replacing it with a 22 gauge speaker-wire; you will still read 12volts on the supply side, but the starter will not crank the engine.
A 55 watt headlamp should draw about 55/12.5=4.4 amps; besides the starter, that is one of the highest draws on the system; it needs a decent circuit. If either the bulkhead connector or the F-link is fried, with just one strand still working, A VOM will still read near battery voltage, but about the only thing that will still work on that circuit is the dashbulbs or possibly the domelite.
Ima thinking it's a poor ground, cuz that would act the same. The electrons are lining up like Welfarewomen on payday, all waiting their turn to pass thru the ONE bank teller.

 

[Dana67Dart]

I believe the 4th picture above illustrates the only condition that you can have 12 volts on the ground side of the terminal with a good bulb intact.
The 2nd photo shows what the meter would read with a good ground, 0 volts

I can test at the headlight terminal where the NEW bulbs is inserted and I have current at ALL the bulb prongs, even the ground.

Same thing at the low beam and high beam bulbs.

I unplug the bulb and test the terminal and just the wire that should be hot is hot.

 

[Dana67Dart]

But say you wired the bulb with a single .007 strand of wire, choking current flow, same as if the the bulb on the car had a high resistance power connection. You would still have 12 volts on the power supply side,but the bulb would not lite, and the filament just becomes a resistor-wire. But since it cannot draw enough power to heat up, now it is just a piece of wire, so whatever voltage went into it, near same comes out.
If you try this with a regular wire it just burns up, but that filament was designed to not burn up.

I'll go with you here and I agree if there was enough of a bad connection the light would not light but you would get a DVM to read ~12V.

the thing is OP posted that he can get 12V on the ground side WITH the bulb in place and the only way that could happen is if there was no ground to the ground side of the terminal. A simple resistance test between ground side of the terminal with all the the bulbs removed and battery negative should prove there is a missing ground

 

[barbee6043]

I appreciate all the input, I really do. This gives me plenty to check out tdoay and maybe tomorrow. Today has already got a list of other stuff we have to do! The list was long when I got up at 6 am!
This car is a 62 Lance I got couple years back. I had several other cars that got my attention. The slant turns over, I changed it over to Mopar ECU deal, I never got around to getting it running... did all the rust/body work back then, but never really got back to it much till recently.
I know it has full 12 v. in and out of firewall. I have pulled the instrument cluster best you can, but on these early cars, the metal part of the dash is really in the way to get under it all to see anything like headlight switch hardly at all.. I did by pass the amp gauge. I know the wiring on this sucker is really OLD. Wife has claimed this TOAD, so I have to keep at it!
The headlight wiring on this beast is somewhat different than those 63 up. It has a pigtail that plugs into the main headlite hardness inside the headlight buckets, and there it that grounds inside that bucket. I had cleaned that ground good. I was wondering other day working on it , IF the ground is not good there at the headlight bucket, maybe I need to splice INTO the grond wire there and run another ground to radiator suppport?
Hopefully this afternoon I can take everyone's info and get some v. readings and clean all other grounds and have results. The bulbs are new
This old Toad was used on a Mo.dirt track years back as the pace car!!!
Hopefully I can check it out some this afternoon!!

 

[Frank Mopar]

Buy a Power Probe.

 

[barbee6043]

Buy a Power Probe.

I had never seen those. I bet I would not be smart enough to work all the things it does!! I thought I was extravgent when I gave $10 for a multi meter!!! Maybe Santa will bring me one!!

 

[Hyper_pak]

Here are the pictures I told you about. Remove the printed circuit board, you can undo the wires as you pull it forward. Reach through the opening and remove the wire plug from the headlight switch. Remove the tall nut on the switch and remove switch from behind. Either that or do what I did, blow it all apart and take 10 years to put it back together.

 

[barbee6043]

I have gotten the headlights all working. I remember 4 yrs ago when I picked up this Toad cleaning all the grounds but I have also added one from Neg Batt. terminal to rad. support like all the 63 up cars have. Also replaced 2 of the bulb sockets, and a ground wire to sockest on one side of headlite bucket. I have a little volttage drop from firewall to connectors at headlights. No doubt the wiring is 50 od years old, I did clean all terminals too.
I noticed after I had gotten th dash somewhat apart someone had spliced into the black main wire at headlight switch. I can npt get to it right now to see exactly what or why.
This Toad was a pace car at a dirt track in Mo. years ago. It had a 2 way radio, fender flags, and a toggle swicth to turn the back up lites on and off!
Thanks for all the input. Life is good ( as soon as the humidity and temps drop a little!)

 

[Dana67Dart]

Glad to hear you solved your missing ground issue.

 

[barbee6043]

Glad to hear you solved your missing ground issue.

Thanks to all, I also got a new Neg. OLD. with the extra wire to ground to rad. support. I also just now figured out another point. When I took the headlight buckets the ground was being grounded there. I just now saw in the FSM these should be grounded at the radiator support. I did run an extra ground to the rad. support from Batt. neg though.
If there is another problem, I know, Go check grounds first.
My wife has to make me copies of you guys diagrams for future reference.!! Thanks all.

Next will be to try to get it started. My compression test was really BAD, but I did pick p another slant. I have poured half a qt of 30 wt down the carb, and got them running. I have another slant I can use but it is getting hard for old farts like me to change all that out!