Turn signals don’t work when headlights are on

[121gigawatts]

Hello everyone!
69 dart gts, 340- 4 speed:
Turn signals don’t work when the headlights are ON. They do work when the headlights are OFF, although, left is a bit slower. I’ve cleaned the fuse contacts, replaced all the fuses, replaced the emergency flasher switch and had pulled the headlight switch. I have power at B1 & B2 in the headlights switch. I plan on pulling the cluster out and trying to poke and clean around there too. I’ve dug around on FABO A lot but couldn’t find this specific problem. Any help would be appreciated! Thanks!!

 

[rattler]

Hello everyone!
69 dart gts, 340- 4 speed:
Turn signals don’t work when the headlights are ON. They do work when the headlights are OFF, although, left is a bit slower. I’ve cleaned the fuse contacts, replaced all the fuses, replaced the emergency flasher switch and had pulled the headlight switch. I have power at B1 & B2 in the headlights switch. I plan on pulling the cluster out and trying to poke and clean around there too. I’ve dug around on FABO A lot but couldn’t find this specific problem. Any help would be appreciated! Thanks!!

ck park light and taillamp bulbs maybe somewhere someone put a single contact bulb in bill

 

[67Dart273]

Poor grounding at socket
Poor contacts in socket or contact pigtails mis-oriented rotationally (clocking)
Wrong bulbs in at least one socket or bulbs jammed in wrong "clocking" or shorted bulb

What usually causes this is that park/ tail power "feeds back" due to a problem and changes the circuit.

 

[KudaKid]

Poor grounding at socket
Poor contacts in socket or contact pigtails mis-oriented rotationally (clocking)
Wrong bulbs in at least one socket or bulbs jammed in wrong "clocking" or shorted bulb

What usually causes this is that park/ tail power "feeds back" due to a problem and changes the circuit.

I have the same issue on my Cuda, only affects the drivers signal lite. I have relamped and correctly clocked the bulbs. I have cleaned out the sockets as best as I can. When looking at the schematics I have trouble following the grounds for the park/turn signals. Are they in the housings themselves ? What switches over to ground when the lights are on and the turn signal is applied ? Oh and I have continuity to both contacts in the sockets. I wouldn not pull the cluster out definately in the housing.

 

[67Dart273]

Sometimes you have to "improve" the grounding. If nothing else, clean and solder a pigtail ground right to the socket shell.

You can troubleshoot and "prove" the problem by getting the problem to "show". While the problem is thus happening, stab a test lamp or meter directly onto the side of the socket shell. Stab the other probe into ground, be sure to get through paint, etc. If the socket is ungrounding you wil l read a voltage.

If that shows nothing, carefully probe the actual lamp shell thorugh the slots.

OR IF NOT JUST WIGGLE THE SNOT OUT OF THE BULB LOL

 

[67Dart273]

"How this works".

A poor ground creates a series circuit. Normally the tail power goes to the tail filament, the stop lamp power goes to the stop/ turn filament, and they are both grounded through the shell

If the lamp comes ungrounded, ......................

With the tail lamps off, all tail and park filaments are in parallel to ground. This creates a fairly low resistance circuit, and if the shell is ungrounded, all four tail filaments provide the series ground

If you tromp on the brake, or turn on the signal, these four tail/ park filaments carry the stop lamp power from the "shell" end of the stop lamp filament through all four tail filaments to ground.

This "works" until you turn on the park/ headlamps. Now the tail lamps are powered, and the ungrounded shell no longer grounds either the tail filament OR the stop/ turn filament WHEN THE STOP LAMPS or signals are on, they work "opposite." That is, with the brake unapplied, NOW the stop/ turn lamp filaments are acting as ground for the TAIL lamp that is ungrounded

 

[KudaKid]

If I am losing a ground , then why does the light stay illuminated ?Is the ground dropping off for just the signal portion ? This only seems to affect the front signal(drivers).

 

[RedFish]

I have the same issue on my Cuda, only affects the drivers signal lite. I have relamped and correctly clocked the bulbs. I have cleaned out the sockets as best as I can. When looking at the schematics I have trouble following the grounds for the park/turn signals. Are they in the housings themselves ? What switches over to ground when the lights are on and the turn signal is applied ? Oh and I have continuity to both contacts in the sockets. I wouldn not pull the cluster out definately in the housing.

What model B'cuda makes a difference. The 67 bulb sockets are crimped into a pot metal housing in a metal grille so that is the chassis ground path. we have seen these sockets loose in the housing.
The later models with plastic housings require and should have a actual ground wire routed to core support.

 

[KudaKid]

What does wire L6A18BK/Y in the wire diagram act as the ground for the opposite lite ? Trying to upload pdf. Check pg 5

 

[KudaKid]

What model B'cuda makes a difference. The 67 bulb sockets are crimped into a pot metal housing in a metal grille so that is the chassis ground path. we have seen these sockets loose in the housing.
The later models with plastic housings require and should have a actual ground wire routed to core support.

69 model year. I have cleaned the headlight grounds, but looked at the assembly and figured the ground was internal as looking at the wire diagram.

 

[67Dart273]

What does wire L6A18BK/Y in the wire diagram act as the ground for the opposite lite ? Trying to upload pdf. Check pg 5

It doesn't "act as a ground." That is your park/ tail power jumpering over to both lamps. That is poorly drawn. The diagram might lead you to believe those wires join at the lamps. In fact each wire to each lamp goes to a different filament, one goes to park, one goes to turn. The ground is the little "dashed arrow" sign pointing down from the lamp

In this case the aftermarket diagram from MyMopar is actually drawn with more detail and accuracy

If you look where I left my "mouse" when I took the shot, this terminal is the jumper wire for the park circuit that interconnects the left and right park filaments. Also, this is drawn more like what the lamp SHOULD look like in schematic form. You have two filaments with a common ground.........two lamps in one

 

[KudaKid]

It doesn't "act as a ground." That is your park/ tail power jumpering over to both lamps. That is poorly drawn. The diagram might lead you to believe those wires join at the lamps. In fact each wire to each lamp goes to a different filament, one goes to park, one goes to turn. The ground is the little "dashed arrow" sign pointing down from the lamp

In this case the aftermarket diagram from MyMopar is actually drawn with more detail and accuracy

View attachment 1715540068

If you look where I left my "mouse" when I took the shot, this terminal is the jumper wire for the park circuit that interconnects the left and right park filaments. Also, this is drawn more like what the lamp SHOULD look like in schematic form. You have two filaments with a common ground.........two lamps in one

Next chance i get I will try to ground out the bulb socket outer case to see what if anything changes.

 

[RedFish]

Specific to front lighting issue; When a front park/turn 1157 looses chassis ground, park lamp current will use turn circuit seeking a ground. This will light up a turn indicator in inst' panel. I suppose there are a few Darts remaining that dont have bulbs in the turn indicators ( bean counters left them out ( early 69 if my memory serves ) to save a coin until customer complaints poured in ). In that case this tell tale sign of front fixture ground fault doesn't help.
Grounds in general; Once the negative side of a circuit reaches the chassis, in this case core support, it still needs to reach the negative battery terminal. For many, a single factory jumper between firewall and engine then through engine block to neg' battery cable served forward lighting and everything else that is chassis grounded. So that ground symbol of dashes on a diagram could be considered a hint, a questionable path.
At some year model ( I'm not sure when ) the factory added a ground jumper directly from core support to negative battery terminal. Those who don't have this jumper will benefit from its addition.
There are a lot of threads about positive supply and path, improving charging system, head light relays, etc...
The most common mention of improved negative path is adding a jumper wire from instrument panel to dash.
Neg = neglected?

 

[KudaKid]

Specific to front lighting issue; When a front park/turn 1157 looses chassis ground, park lamp current will use turn circuit seeking a ground. This will light up a turn indicator in inst' panel. I suppose there are a few Darts remaining that dont have bulbs in the turn indicators ( bean counters left them out ( early 69 if my memory serves ) to save a coin until customer complaints poured in ). In that case this tell tale sign of front fixture ground fault doesn't help.
Grounds in general; Once the negative side of a circuit reaches the chassis, in this case core support, it still needs to reach the negative battery terminal. For many, a single factory jumper between firewall and engine then through engine block to neg' battery cable served forward lighting and everything else that is chassis grounded. So that ground symbol of dashes on a diagram could be considered a hint, a questionable path.
At some year model ( I'm not sure when ) the factory added a ground jumper directly from core support to negative battery terminal. Those who don't have this jumper will benefit from its addition.
There are a lot of threads about positive supply and path, improving charging system, head light relays, etc...
The most common mention of improved negative path is adding a jumper wire from instrument panel to dash.
Neg = neglected?

I just had my instrument panel restored at Instrument Specialties and added a ground wire down to the base of the steering column from the panel. I am waiting for a new negative battery cable to come in from Mancini racing and have read about adding a ground to the radiator support to the negative on the battery cable so I will be adding that as well.

 

[67Dart273]

Grounds in general; Once the negative side of a circuit reaches the chassis, in this case core support, it still needs to reach the negative battery terminal. For many, a single factory jumper between firewall and engine then through engine block to neg' battery cable served forward lighting and everything else that is chassis grounded.
The most common mention of improved negative path is adding a jumper wire from instrument panel to dash.
Neg = neglected?

A good way to improve battery--to--body ground is (V8) on the rear of the driver side head are the same holes that are on the front of the pass. side head. Use a short bolt and use an "eye to eye" starter cable about a foot long and bolt to the firewall or the master cylinder mounting stud

The great thing about Mopars is that once you DO get the battery solid to the body, then the body is pretty much welded. So if you get a good clean connection at the "other end" you have it.

(^^This statement may not apply for EFI etc with EMI sensitive circuits that is another matter)

 

[KudaKid]

Ran a jumper from the core support to the bulbs pig tail base and YES, it works. Did not flash as fast as the driver's side but it definitely works. Can these pigtails be separated from the housings ? I have a few spares that I can just check to see if they work as well. On another note what size wire should I run from the battery negative to the core support ? Thanks for all the support everyone.

 

[RedFish]

What size wire should I run from the battery negative to the core support ? Thanks for all the support everyone.

I dont know. I don't like addon wires at battery terminals. While at the parts yard (LKQ) I picked a ground cable with the 2nd wire built in. I forget what it was on. Was there to gather various sizes of split loom and other wiring upgrade needs. Retailers ask far to much coin for some things.