Signal lights won't blink, simply stay on

[agv18]

Hi guys, I was hoping someone could give me some guidance on an issue I'm currently having with my 1972 Plymouth Scamp. Currently, the tail lights and the signal lights are not working. The brake lights work when I press on the pedal, but if I turn on the lights, nothing happens in the back. Also, the signal lights don't blink; they just stay on. The hazards work, as well as the headlights and side markers. I have changed all the fuses, put new bulbs in, checked the bulb connectors, and changed the flasher for the signal lights, and I'm not sure what else could be the issue. The only thing that comes to mind is that the fuse box had decent oxidation at the connection points, but I cleaned it pretty thoroughly with a wire brush and contact cleaner. Any help is greatly appreciated!!

 

[67Dart273]

First, the tail circuit is completely separate from signal, and the hazards have a separate flasher from the turn signals, as well as a different power source, as they are powered all the time. The signals may have a bad flasher, blown fuse, etc You can download a factory service manual for free, from MyMopar.com.

You say the side markers work, does that include the rear? If so, this is starting to sound like a bulb/ socket problem

 

[1WildRT]

The flasher near the steering column is for the hazard flashers.... The turn signal flasher is near the passenger side of the radio... Light coming on but not flashing points to a bad flasher..

Do the front parking lights Work? Dash lights work? Check for power on the black wire with the tan tracer at the bulb sockets... If you have power check the grounds, but the fact the brake lights work tends to indicate the grounds are good... So try another bulb, just today I was working on a car with two new bulbs that were bad....

 

[agv18]

Yes, all the side markers work, including the rear. I put new bulbs in and cleaned out the sockets because there was also oxidation there. Also, I changed the flasher for the turn signals; the hazards one was working fine. I'm downloading the manual in case I find something there. Thank you for that!
Also, the parking lights work, and the dash lights work sometimes but not currently? I'm not sure if that has anything to do with it. Also, it might be stupid, but I was just messing with the lights and I noticed that if the turn signal is on, the brake light won't work. Sorry if any of my questions are idiotic, but I'm still fairly new to wiring in general.

 

[1WildRT]

If the T/S switch isn't centered one brake light won't work.... Mopars of this vintage use the same filament for brake light as the T/S..

Dash lights check the dimmer switch, Front park lights are fed from the same fuse as rear park lights and the dash light fuse is fed from the same park light fuse...

The fact you changed the T/S flasher & it still doesn't flash points to bulbs not drawing enough current to cause the flasher to work... Are the bulbs LED's? If so they require a flasher that doesn't use the bulbs current demand as a way the trigger the flasher...

 

[agv18]

Oh, so if the T/S isn't centered, the opposite brake light won't work? Currently, if I try the left T/S, the right brake light won't turn on, and vice versa. Also, the bulbs are halogen, and I bought a new dimmer switch already. The car is a new purchase that was sitting for a while, so there are a lot of kinks I haven't learned yet. Thank you for all your help, by the way!

 

[RedFish]

There is 1 filament for brake and turn. The switch switches both the direction and the power source. Switch centered, both get brake power. Switch left, left gets flashing turn power while right remains on standing brake power and vice-versa

 

[diymirage]

i had similar issue (at least with the indicators) with my 71 duster
i have a 69 valiant grille and it has dual filament bulbs in it, one being a turn signal, the other a running light

with the running lights off, the turn signal worked as they should
with the running lights on, the turn signal would NOT do anything, but the turn signal indicator on the dash would turn on and stay on

this only happened to the left side of the car, the right side worked fine
so i looked for visual difference and i notices the right side of the light was properly grounded to the chassis and the left was not

as a test i ran an extra ground wire (just a length of wire with two alligator clips) from the offending light to the battery and that solved the issue

 

[RedFish]

That is a very typical fault. At one-time GM ran front socket ground through side marker 194 bulb filament. Thus on with park lamps and sort of flashing with turn. If a dash indicator came on with park lamps, that side marker bulb was bad. Current seeks ground and finds it through the park lamp filament.

 

[68Bee]

Check all the grounds again, with a jumper from battery to side of socket. I have also seen a broken bulb filament shorting against the other filament cause all sorts of issues.

 

[agv18]

I completely forgot but one the side marker bulb because it is bad, hopefully it's just an easy fix as switching that bulb! If not I will check all of the listed. Thank you so much guys, your help is greatly appreciated!!!

 

[RedFish]

I completely forgot but one the side marker bulb because it is bad, hopefully it's just an easy fix as switching that bulb! If not I will check all of the listed. Thank you so much guys, your help is greatly appreciated!!!

I didn't state that your vehicle was wired in that manner. Your side markers may not be related at all to your issue. Forgive me if I caused confusion.

 

[agv18]

Oh no you’re fine! No confusion, I just wanted to look at all the wiring in case I missed anything! Again thank you!

 

[michiganpat]

yeah, don't totally discount the turn signal switch either. I had a bunch of taillight issues, spent a day tracing wires, checking grounds, etc, and it ended up all being the switch in the column.