Headlight Issues

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PanzerschreckLeopard

PanzerschreckLeopard

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Yeah, another one of these threads.... 1971 Valiant.

Well, so, one day I drove to work, and the high beam indicator never seemed to go off....just "on" and "on but slightly dimmer," even with switch off. Get there and discover the headlights don't work.

Trying to check things today, and:

Switch seems to work.

Hazards and Dome and any other lights work.

Foot dimmer switch does not work correctly (Either the Centre pin has continuity to the Red "high," or it doesn't have continuity to either outboard pin), BUT, bypassing the dimmer switch with a jumper does not solve the issue; it will still do the same behavior with the high beam indicator light, being "slightly dimmer" and then goes "on" when I jumper the centre pin to either of the others, with the lights not being on.

Finally, I remove both the headlights, and find that, with the foot switch still disconnected, both of the outboard pins have about 5 ohms to ground, and the centre pin is open.

So, what should I look at next?
 
I'd swap the seal beams to see if it's the bulb or wiring.
If condition still existed, I'd clean the ground connection at the rad support beside the rad and/or supply an independent ground to the seal beams, middle? contact I believe .
If the electricity can't find a ground down at the bulb, it often seeks the only ground it can, back up the harness hi-beam wire and thru the hi-beam indicator on the dash.
Cheers
 
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Right then, I'll try those tomorrow--I can also bring home a power supply from work that shows current draw.
 
Do you have a wiring Diagram?

if not you need one. MYMOPAR.com free download or Classiccarwiring.com has laminated full color diagrams very reasonably priced.


So lets assume for a moment that all your wiring and switches are good....

  1. get a small lightbulb (like a dome light or even tail light) and some jumpers, wire up the light bulb to make a test light out of it. a commercial test light that uses a neon or LED is not the same as a incandescent test bulb, not enough load
  2. then with the headlight switch on and the high beam switch connector disconnected see if the light will light up between ground and any of the 3 terminals in the connector. If it lights up on one and none of the others, that's a good sign. (in 67 it is the light green wire in the connector that comes from the head light switch and should have power)
  3. put the high beam connector back on the switch
  4. next remove the headlight bezels and the headlights, do the same test on the each of the 3 terminals in the headlight connector (in 67 Red is high beam and black is low beam) if the high beam switch is in low beam mode the test light should light between ground and the black terminal ( same for high beam mode but n the ted wire.
  5. If that all checks out put the test light between battery plus and the ground terminal in the head light connector (in 67 its black with white tracer) If the light lights, then your ground is probably good
  6. That only leave the bulkhead connector



NOTE: be sure you can tell the difference between the test light being full on and on but dim.

The reason to use a test light is to add a load to the wires.

A volt meter can read full voltage on a wire that has only one strand still connected, BUT with a load that one strand will generate so much resistance that a higher load with not function.

Ohm meters are the same, they can tell you that there is continuity on a wire but not the condition of the wire.
 
I would guess the hi beam indicator is actually a separate problem. The clusters in these girls are only grounded by the mounting screws. If the cluster becomes partly ungrounded, you can find silly stuff going on.

Start by replacing the dimmer, they are not expensive. Then monitor the voltage to the hi beams side and switch it back and forth while observing the voltage at the dimmer hi beam terminal as well as the behavior of the hi beam indicator. If there is no voltage, and it still glows, then the lamp is getting power thorugh the lamp shell.

I would also check the ground for the headlamps. They are all (normally) tied together to just one ground lug, somewhere on the radiator support.
 
Right then, I'll try those things when I get a chance. As for wiring diagrams, I was using the ones from the 1971 Service Manual.
 
Bad ground somewhere, weird things like this are almost always bad grounds. Could also be a headlight bulb with a filament shorted to the other side.
 
67Dart273 said:
I would guess the hi beam indicator is actually a separate problem
Click to expand...
High beam indicator taps off the high beam feed at the firewall. So if power is getting to the indicator it's getting to the firewall connector.

OR

there is a shorted wire under the dash
 
Right then, found a bad ground....in fact, the ring terminal was completely disconnected. What baffles me is that I don't see any missing screws or ground lugs it could have fallen off of. The only ground lug near by had clearly not gone loose, but I put it on there and now the issue's gone. (I did have to replace the dimming switch though.)

Took the chance to replace the headlights as well...the old ones were pretty dim, though now I wonder if the ground issue might have contributed. (Never had any flickering of em though.)

Thanks for help all, sorry that it turned out to be a simple issue.
 
Vibration, heat, those wires up front and in the engine bay go through a lot.

Dimmer switches I have never had issues until last week. But its not uncommon for those switches to give out under years of use and being in a location with wet shoes etc dripping on them.

Headlights.
Here's the deal. Yes towrd the end of their lifespans they will be a little dimmer than when brand new.
Yes. The poor ground played a big role in the bulbs producing less light.
If everything was perfect, the voltage across the headlights with engine running would be around 14 to 14.5 V.
With resistance in the dimmer switch, resistance at the poor failing ground, plus the long distance the electrons need to go through 18 and 16 g wire, plus a headlight switch, the votlage across the bulbs might have been 10 V or less.

Your 1971 came with 6012 sealed beams. Sometimes marked with a 2 on the glass.
Nominal rating each 50/40 Watts high/low.
Replacements are generally something that draws more power, but always.
6014 Nominal rating 60/50 watt (Came new on Chrysler products a few years later)
H6014 60/40 W (around 1977) H indicating a halogen
H6024 Since 1984, and typically (but not always) with 35 watt low beam.

Dan Stern has suggested looking for new old replacements if one is sticking with sealed beams. The products currently made are generally produced on very worn molds etc and quality is not as good as stuff made in the 1970s.
If you drive a lot at night on roads that need good light than look into a relays powering the lights more directly from the alternator, and consider the Hella "Vision Plus" US DOT lamps with some good bulbs as a relatively reasonably priced upgrade. A few months ago some guys were able to buy Kioto kits direct from Toyota for a great price for good lamps and relays.

To rough check headlight aiming if you don't have access to an aimer.
www.forabodiesonly.com

1973 Dart headlight aiming diagram

Hello, I need to aim the headlights on my 1973 Dart Swinger. I know how to do it but I need the diagram with how far away from the wall the car should be and how high to aim the beams. My 73 Dodge service manual said this info was in another book, the body manual. Anybody out there have a 73...
www.forabodiesonly.com www.forabodiesonly.com
 
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