69 valiant electrical gremlin turn signal and license plate light

[Mattax]

Here's a diagram of the turn and park lamp wiring for '67B. Some colors may be differnet but the concept is the same.

Since the bulbs share the socket for a ground, one path for electricity to complete the circuit is through a bulb's second filiment. Follow the orange line representing current out of the front turn lamp. It flows through the second filiment into the parking lamp feed wire. Then to the right tail light and out the tail light ground.

 

[sketch]

So the electricity is finding another path to ground.
This almost certainly relates to why it doesn't work with the parking lights on.
With the lights off, current was flowing back through the parking light circuit.
Exactly to where I'm not sure. Maybe Murray or Redfish will know.
I always need to look at drawing for these circuits. I didn't want to do that until I knew if the car had any optional features.

put the one that works with the ground out works flawlessly no matter what. It is the drivers one that is all janky.

 

[Mattax]

put the one that works with the ground out works flawlessly no matter what. It is the drivers one that is all janky.

Well you can think about what's in post 26. Sketch out what you've got on your car and that may help you picture the problem. Any disconnected ground will cause the lectrity to seek another route - even if means going through some resistance (the light bub filiments)
I'm going to dinner!

 

[sketch]

Turn signal- I see two wires going to it. Are there two connecters on the bulb/ two filaments in the bulb? This means that your turn signal housing does two things- it is a park light and a turn signal (two things). This in turn means there is no third wire- a ground. These ground through the metal housing. Since most park lights are mounted in plastic grills (which insulates it) there must be some provision to ground the housing. Look closely at the wire loom.There must be a third wire to ground the housing. Both sides need to be grounded.

you saw the pictures of the passenger one right? that is the third ground wire i think? on the passenger side, it doesn't need to be plugged in for it to work fine whereas the driver side light HAS to have the ground plugged to it for the light to function in any capacity.

 

[sketch]

Well you can think about what's in post 26. Sketch out what you've got on your car and that may help you picture the problem. Any disconnected ground will cause the lectrity to seek another route - even if means going through some resistance (the light bub filiments)
I'm going to dinner!

thanks for your help so far sir.enjoy

 

[Mattax]

What I have done, and maybe is the best direction right now, is check that all the bulbs are good (both filiments) and properly seated in their sockets.
Also check all of the connections, especially the grounds.

After that is all done. Then do a systematic functional check.
Turn on the parking lights. Walk around and see if they are all the same brightness.
Turn them off.
Turn on the right turn signal. Walk around and see what each lamp is doing, how bright.
Turn on the left turn signal. Walk around and see what each lamp is doing, how bright.
Turn them off. Turn on the Hazzards. Walk around and see what each lamp is doing, how bright.

Now you have a pretty good list of what is working and what is not.
Turn the parking lights on and recheck the turn signals and hazzard.

If anything is amiss, with the complete list should be able to narrow it down.
Put the battery on a slow charger since all that testing is draining the battery. Charging it on the charger will save other potential headaches later...

Here's the front end lighting diagram from the 1969 Dodge Dart-Coronet Charger Service Manual.

You say your car is without the fender mounted indicators. So just erase those.
You can download the manual as a pdf from MyMopar - Mopar Forums & Information - Service Manuals

 

[sketch]

I will do this tomorrow. There is no chance it is a fuse, is it? I used the light tester on fusebox and it never put up. Mind you, I can't remember if I had the car turned on.

 

[Mattax]

I will do this tomorrow. There is no chance it is a fuse, is it? I used the light tester on fusebox and it never put up. Mind you, I can't remember if I had the car turned on.

I'm still up.
Not likely the fuses.
All of the parking lights are on a single fuse. Same fuse is usually shared with circuits such as stop light.

The turn signals and hazzard, if they have a fuse, will also share just one fuse.
The turn signal and hazzard flasher units work sort of like a circuit breaker. When enough current flows through them there is a bimetal connection inside that heats up. When it is hot enough it and bends away from the contact. Once it cools it touches again.

 

[Mattax]

I used the light tester on fusebox and it never put up.

Two or three fuses get power only when the key is in Run or Accessory.

Two fuses are connected to the power all of the time.

One fuse only gets power when the parking lights are on.

Unlike inside a building, the fusebox is not the main distribution center.
Power to run things gets distributed from the junction drawn as a big black circle. (That's a welded splice.)
In my '67, the brake lights, dome light, and parking lights all share the same fuse.

from the '69 service manual, "Battery Feed" is the power from the main splice. The main splice is connected to the battery so this wire always has power.

Accessory feed Q2A is from the key switch. It only has power when the key is in run or accessory positions.
"Tail Light" is again a shorthand. I followed that wire on the diagram and it goes to the headlight switch B2 terminal. So that fuse is for all parking lights.

Here's what it looks like in real life.

(in this case the one in my '67 Barracuda so some small differences from '69).

 

[sketch]

okay. Here is what happened after the systemic check:

• all bulbs replaced and checked that they were seated correctly
• when parking lots are on, the indicator light on driver side (the one that has not blinked when parking lots are on) is the brightest
• with parking lights off, both blinkers work however the passenger blinker light in front is brighter (which is opposite of when they are just on in parking lot on mode)
• if i remove the ground wire from the passenger indicator light, the light still lights in parking lot mode, and when using the blinker, either with or without parking lights referenced in post 24.
• for the driver side indicator (the one that has been a bugger), if i disconnect the ground the light doesn't work at all (
• Back lights are the same brightness no matter what mode is used. parking lot on and off blinkers, they are identical
• Headlights are constant and the same brightness no matter what i do. They are equal brightness.
• Obviously something has to do with when parking lights are engaged.

I don't even know where to check for the ground issue, or whatever it is. Any suggestions friends??

 

[Mattax]

OK.
I'll need sketch it out myself.
I made an error last night. I confused your car for someone else and I thought the front parking lights were on the same terminal as the tail lights.
The '69 Plymouth manual shows the front lamps were still on their own terminal. This means they should turn off when the headlights are on. In other words, one click out on the headlight switch turns the parking lights and tail lights on. Two clicks out turns the headlights on, tail lights on, front parking lamps off.
Is that what you observe on your car?

At some point in time that arrangement was changed, that's why I ask.

 

[sketch]

OK.
I'll need sketch it out myself.
I made an error last night. I confused your car for someone else and I thought the front parking lights were on the same terminal as the tail lights.
The '69 Plymouth manual shows the front lamps were still on their own terminal. This means they should turn off when the headlights are on. In other words, one click out on the headlight switch turns the parking lights and tail lights on. Two clicks out turns the headlights on, tail lights on, front parking lamps off.
Is that what you observe on your car?

At some point in time that arrangement was changed, that's why I ask.

Yes. Exactly. One click is parking lights two clicks all lights.

 

[Mattax]

The front parking lights stay on when the headlights are on?

Do all lamps blink equal with the hazzards on?

 

[Mattax]

The other guys may be more familiar with the lamps and wiring on your car.

At moment I can't see how the right parking lamp is and turn signal is working with no ground.

 

[Mattax]

I think the left (d/s) lamp assembly or bulb is connecting the park and turn signal circuits.
So with the parking lights on, there is 12 V on both sides of the turn signal filament. So no current can flow through it.
Additionally with the (p/s) ground disconnected, somehow its getting completing circuit through the driver side ground

If its possible try to switch the two.

Really maybe the easiest thing is to buy a powered test light or a multimeter. Then check for connections.

 

[sketch]

Okay so now I feel like an idiot. I took bulb out and held it in the position you see in photo and had my son flip lights on ,etc and the all worked. Issue now is I can’t figure out how to get bulb to stay in. There is a low bump amd a high bump on the lights obviously to say which way it goes in. When i had it on backwards it was causing parking light to cut off return. I am sure I am overthinking but how do I get the darn bulb In?

 

[Mattax]

Maybe something got distorted. or the bulb was made backwards.
I assume you know its a bayonet socket. Push in, then 1/4 turn clockswise, release.
Obviously with the dual contact it won't fully go into position if not in the correct channels.

 

[sketch]

That is the issue. I can see where the slots are and I push it in gently but can’t get the 1/4 turn. Crazy thing is the bulb can go in backwards but then blinker doesn’t work. I thought maybe there is a trick or something as the bulb should only go in one way.

 

[RedFish]

you saw the pictures of the passenger one right? that is the third ground wire i think? on the passenger side, it doesn't need to be plugged in for it to work fine whereas the driver side light HAS to have the ground plugged to it for the light to function in any capacity.

That is the issue. I can see where the slots are and I push it in gently but can’t get the 1/4 turn. Crazy thing is the bulb can go in backwards but then blinker doesn’t work. I thought maybe there is a trick or something as the bulb should only go in one way.

I suppose there could be something wrong with the socket. They are quite simple and were quite dependable when new. In the bottom of the socket is a small board with 2 little contact. Those contacts are on the ends of the 2 wires. A spring beneath the board allows it to move up and down in the socket so the wires move a bit too. Rust down in the socket along with stiff wires can interfere with board movement.
The 2 little tangs on the bulb are 180 degrees apart so the bulb can start in 180 degrees wrong. If the board doesn't move down far enough the bulb tangs wouldn't go deep enough to reach the groove/route where they turn. If the bulb is 180 degrees wrong it wont go deep enough to turn regardless.
You could have a broken board, or spring, who knows?
Rebuild kits for these sockets are available at Amazon, etc... 68130 by GROTE - Replacement Lamp Socket Repair Assembly - Double Contact, 7 1/2" Long
You'll have to get the wiring correct to bulb orientation. The park lamp wire is the same color wire for both left and right fixtures. So temporary hook up that 1 wire to new socket wiring and pull the park lamps on. If this bulb is a much brighter that the other, you have park circuit tied to turn element of bulb. Move the temporary connection to other wire and confirm both park lamps the same brightness. Complete both wire connections, done.

 

[sketch]

apparently, less force is better. bulb in and everything works!! thank you all!!