Rear lights...whats normal?

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ACME SS

ACME SS

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I have a 71 Demon with tail light issues. I do have a schematic however I'm not positive the lights worked properly before I noticed the turn indicators not working the other day. And what I mean by that is I never checked them with the brakes on.

Without frying my melon with the schematic that is split into 2 sheets, I thought perhaps someone could tell me what "normal" is so I can have a bit of a head start. Here is what my current conditions are, I'm curious what is correct and what is wrong? Thanks in advance

Headlights ON---Tail lights on dim (seems correct)
Headlights ON, Brake on---Brake light comes on (seems correct)
Headlights OFF --Nothing (correct)
Headlights OFF, Emergency Flashers ON---Flashers flash bright like brake filament
Headlights OFF, Emergency Flashers ON, Brake ON---same as previous scenario, no way to know brakes are on (seems suspicious, wondering if wrong filaments are being energized for emergency and signals?)
Turn Signals Left or Right--Stopped working although a few times one or the other will blink once or twice which is obviously wrong
Turn Signals (not working) and brake is applied---The brake light on the side the signal is on goes out and there is no signal in rear or front (I'm thinking there is a short to ground somewhere?)

Also, when the brake light is ON, BOTH filaments light up and when I remove the socket from touching ground, the lower filament goes out and the taller filament stays lit but dims down.

I know a lot of this is wrong but it would be very helpful to know how it should be. I have run a separate ground to the light housing so I don't think a lack of ground is an issue. I know everyone likes a picture but there isn't much to photograph on this one.
 
So far as diagrams, go to MyMopar and look for a 71 service manual. You may have to settle for Dodge vs Plymouth.

With the hazard flashers on, I believe if you apply the brake they stop and all 4 corners light up. If you are having trouble with turn signals and have eliminated power/ flasher as a prroblem, don't forget that they are tied in with the hazard switch, which is of course a part of the TS switch. It can however introduce problems.
 
ACME SS said:
Also, when the brake light is ON, BOTH filaments light up and when I remove the socket from touching ground, the lower filament goes out and the taller filament stays lit but dims down.I .
Click to expand...

Are you saying you are holding the socket in your hand? If the socket is not grounded, that sort of thing will happen

You are aware? that there are two flashers? One for turn, the other for hazard
 
67Dart273 said:
So far as diagrams, go to MyMopar and look for a 71 service manual. You may have to settle for Dodge vs Plymouth.

With the hazard flashers on, I believe if you apply the brake they stop and all 4 corners light up. If you are having trouble with turn signals and have eliminated power/ flasher as a prroblem, don't forget that they are tied in with the hazard switch, which is of course a part of the TS switch. It can however introduce problems.
Click to expand...
Hmmm. When I apply brakes the flashers don't change at all, i.e., the brakes don't come on.
 
67Dart273 said:
Are you saying you are holding the socket in your hand? If the socket is not grounded, that sort of thing will happen

You are aware? that there are two flashers? One for turn, the other for hazard
Click to expand...
Hey thanks!
I borrowed the hazard flasher for the signal flasher and all the goofy stuff quit...except of course I need to buy a flasher now for hazard. Thanks!
 
Last edited:
67Dart273 said:
It's possible I'm incorrect on that, at least "some years."
Click to expand...
I'll check that when I get a new flasher for hazard as you fixed my problem. Swapped out the turn with my hazard. Thanks again! Don't know why I didn't think of the hazard other than the brakes doing weird stuff.
 
Just to clarify:
In a typical older Mopar, the tail light and parking lights use dual filament bulbs. Can be clear or amber for the front depending on lens color.

With light switch in first position, parking and tail lights are lit using the dimmer of the 2 filaments. These are the running lights.

The brake lights and turn signals share the same filament, the brighter of the two in the same bulb.

Sounds like you found your problem but usually the first thing to check when a turn signal stops working is the front and rear bulb with the car stopped and the T.S. switch on. The unlit bulb is the one to replace as a burned out filament stops that side from working.
 
KosmicKuda said:
Just to clarify:
In a typical older Mopar, the tail light and parking lights use dual filament bulbs. Can be clear or amber for the front depending on lens color.

With light switch in first position, parking and tail lights are lit using the dimmer of the 2 filaments. These are the running lights.

The brake lights and turn signals share the same filament, the brighter of the two in the same bulb.

Sounds like you found your problem but usually the first thing to check when a turn signal stops working is the front and rear bulb with the car stopped and the T.S. switch on. The unlit bulb is the one to replace as a burned out filament stops that side from working.
Click to expand...
Thanks, although it "works", I will look into it closer because all the rear wires had been cut at one point and someone twisted them together. When I was restoring it, I soldered and heat shrinked the wires back together. There has been some strange things from time to time like a dim bulb, etc. For that reason I bonded the housings to a ground bus and that seemed to fix it. I find it mind blowing though when something as simple as a bad flasher can cause so many strange things to happen. I can't wait to tear the flasher apart cause I suspect it is shorted internally.
 
Found the problem! Can you spot it? LOL.

upload_2022-6-30_7-55-36.png
 
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