Paging electrical gurus... courious problem

OK, this one has me stumped.

Turn the "lights" (headlights) on and the left side tail lights light up with both filaments. Right side single "tail light" filament lit.

Checked voltage and the tail light line has 11 volts. Turn signal/brake line has basically 0 volts both right and left.

Remove left side socket from tail light housing and then it lights only the single (tail light) filament. Touch the socket to the housing and both filaments light. With the socket removed from the housing it's my understanding that it should not light at all... the housing is the ground. Right side single element says lit if you remove it as well but only one filament lit as before.

With the lights turned off the turn signals work perfectly as do the brake lights.

Here's what I suspect.... the sockets were aftermarket (Chinese) el-cheapos and I believe they're allowing the turn signal/brake light side to act as a ground. But.. I'm no expert so are there any knowledgeable gurus out there who might have an "educated" opinion on this??

Thanks in advance...

Always start with grounds! Then go from there. Bad grounds will make lights do all kinds of weird things!

Sounds like a bad ground as you suspect

Do you have a good ground strap between the engine block and the firewall?
You can try testing by running a temporary wire from the lamp socket all the way back to the battery. It can be almost any type of wire.
See if your results change.

Don Frelier said:

Do you have a good ground strap between the engine block and the firewall?
You can try testing by running a temporary wire from the lamp socket all the way back to the battery. It can be almost any type of wire.
See if your results change.

Click to expand...

I have a ground strap from the engine to the chassis. All light circuits work properly except the driver's side tail lights. I'll try running a separate ground line tomorrow... have to get more wire. However, the housings are the ground. They're mounted to the chassis with 6 bolts and my voltage tester shows a good ground. With the bulb sockets removed from the housing and the headlight circuit on, the tail light filaments come on..... and they shouldn't. The bulbs should be dead because there is no ground. With the bulbs mounted in the housing both headlight and brake filaments come on. This is true with the brake/turn signal lines connected or disconnected and only for the drivers side. Passenger's side seems to work properly. I'm stumped.

Try removing the left side bulb with both sockets out of the housing and see if the lights go out.

I though this was an issue with the headlights on? Check the headlight ground at the headlight and where the ground connects to the radiator core support.
Another check, if the dash high beam indicator is on, in either foot switch position (low beam) then the low beam is grounding through the high beam and back to the dash.
Have you removed the right side tail light bulb and make sure it is a dual element bulb, and not a single element bulb that might be shorting the Brake and turn signal wires?

Brake / Indicator lights ground at the socket, but the turn signal switch is the main part of the circuit. The Hazzard switch is a minor part of the circuit.
With the hazzard switch on, all the turn and brake lights should flash.

451Mopar said:

I though this was an issue with the headlights on? Check the headlight ground at the headlight and where the ground connects to the radiator core support.
Another check, if the dash high beam indicator is on, in either foot switch position (low beam) then the low beam is grounding through the high beam and back to the dash.
Have you removed the right side tail light bulb and make sure it is a dual element bulb, and not a single element bulb that might be shorting the Brake and turn signal wires?

Brake / Indicator lights ground at the socket, but the turn signal switch is the main part of the circuit. The Hazzard switch is a minor part of the circuit.
With the hazzard switch on, all the turn and brake lights should flash.

Click to expand...

This is a '64 Polara so no hazard switch. The problem is ONLY with the driver's side tail lights when the lights are turned on. Headlights, high/low beams, parking lights, turn signals, dash lights, courtesy lights and indicator lights for turn signals and high/low beams all work properly. All the tail light bulbs are all 1157 and are new, as are the tail light sockets.

black64 said:

Try removing the left side bulb with both sockets out of the housing and see if the lights go out.

Click to expand...

With the tail lights turned on the driver's side lights stay on (single filament) when you remove them from the housing. Doesn't make a difference which one is removed or if all are removed. Once you remove them from the socket just the tail light filament is lit. When in the housing both the tail light and brake light filaments light, even with the turn/brake light wiring totally disconnected.

Try swapping sides with the sockets.

Centerline said:

With the tail lights turned on the driver's side lights stay on (single filament) when you remove them from the housing. Doesn't make a difference which one is removed or if all are removed. Once you remove them from the socket just the tail light filament is lit. When in the housing both the tail light and brake light filaments light, even with the turn/brake light wiring totally disconnected.

Click to expand...

I had to read this a few times, but I think your saying that when the marker lights are on, the brake/turn signal filament in the dual filament 1157 bulb is lit?
Since the sockets are new, I would remove the bulb, and push the wires through the socket it inspect the wires and terminal under the insulator, make sure you don't have a short. The re-assemble, and use a jumper wire to ground the socket to test if it is a ground problem before putting the socket into the housing.

PROBLEM SOLVED:

First, many thanks to all who offered help. Although a 'bad ground" didn't turn out the be the problem it never hurts to confirm the grounds are good. What did cause the problem was ME. Which I suspected was the weak link in the system to begin with.

Today I disconnected all three circuits.... turn/brake circuit for each side and the tail light circuit. I then checked each circuit to make sure all voltages were correct. ie. 11+ volts when on and properly grounded. Then I bypassed the sequential turn signal electronics and hooked up the tail lights only. The result was the brake filament was working on drivers side and tail light filament was working on the passenger's side just like before. So... after a few swear words I switched the terminals on the driver's side bulbs, and that did the trick.

Apparently I had wired the driver's side brake light terminals to the tail light circuit and the tail light terminals were wired to the brake/turn signal circuit on the driver's side only. This is why when the tail lights were turned on, the lights were too bright on the drivers side and the turn signals failed to work properly. After this DUH moment I wired back in the sequential system and everything now functions correctly. See short video below.

Thanks again for everyone's help. It is greatly appreciated. Especially my wife who was kind enough to handle the pedals in the video.

I really like that car.
( And I really don't like white, so I really like it)