[Piercerejr]

Ok, so I have been troubleshooting the turn signals on my 68 coupe, and I am truly stuck. So far I have:

1. Replaced the turn signal switch.
2. Replaced all bulbs
3. Replaced the rear drivers side tail light socket since it was falling apart.
4. Replaced both flashers

So now, all the turn signals work except the drivers side rear one. I know I replaced it, and most may think that is the issue, but ill later explain why I don't believe that is the issue. That particular socket was in rough shape, and wasn't working to being with, so I replaced it to see if that was the issue and it wasn't. So that means, Both front, hood, dash, and the passenger rear all work and flash when activated by the turn signal switch, or emergency flasher switch.

Now in my current troubleshooting, I recently picked up a TopDiag P100pro Car Circuit Tester and have been able to determine the following:

1. Using the component activation feature test that the new socket does function as expected, and when receiving power from the tester at where it was spliced in will light the bulb.
2. The bulb is good
3. I have continuity from where the bulb is spliced in, to where the wire end at the turn signal switch connector.
4. With the turn signal switch connected, I inserted a probe into the connector at the switch side, and when activating the left turn signal and flasher switch I get power going to that particular pin.
5. The light comes on when my day time running lights are on

So there it is that is where I am stuck, no driver side rear turn signal, or driver side brake light, and I am not sure where else to go from here.

 

[Mach1 Driver]

You didn't mention checking the chassis ground for the light. Power "in" is only half of the requirement. If you have to, attach a wire to the housing and run it to a known good chassis ground.

 

[Matter]

Start at the bulb socket and work your way forward. Remove the bulb, with turn signal on probe your test light on the brass pin in the center. If you have power there and your bulb is good then you have a ground issue at the light.
Be sure to confirm that you have a good ground on your test light by probing 12v on a working light.

 

[Piercerejr]

You didn't mention checking the chassis ground for the light. Power "in" is only half of the requirement. If you have to, attach a wire to the housing and run it to a known good chassis ground.

I assumed both the tail lights shared a common ground on tail light wiring harness, which for me is connected to the trunk latch housing. With the old socket, I did ground the socket directly to the body for testing, but can't say I did it with the new one yet.

 

[mustangted1966]

does the brake light on that side work?

 

[Piercerejr]

does the brake light on that side work?

It does not.

 

[Piercerejr]

I assumed both the tail lights shared a common ground on tail light wiring harness, which for me is connected to the trunk latch housing. With the old socket, I did ground the socket directly to the body for testing, but can't say I did it with the new one yet.

I checked and I have continuity between the grounding tab on the socket and the chassis ground point. Additionally the ground would have to be good since I am able to inject 12v directly at the splice point for the new socket and light the bulb on the turn signal wire.

 

[Matter]

If your ground is good and you have current at your splice, then you need to check at the actual brass pin the bulb contacts inside the bulb socket. If no voltage there you either have a bad pigtail or your splice is no good. When you check at the splice you need to be sure you are checking the wire beyond the splice.
If you have voltage at the pin and your ground is good and your sure about the bulb being good, then be sure your pigtail is indexed correctly.

 

[Piercerejr]

If your ground is good and you have current at your splice, then you need to check at the actual brass pin the bulb contacts inside the bulb socket. If no voltage there you either have a bad pigtail or your splice is no good. When you check at the splice you need to be sure you are checking the wire beyond the splice.
If you have voltage at the pin and your ground is good and your sure about the bulb being good, then be sure your pigtail is indexed correctly.

What exactly do you mean by indexed correctly?

The socket has 2 slots with two guide channels at different levels. If you mean turn the bulb 180 degrees, and try to pit it in I thought 1157 bulbs could only go one way due to the offset nubs or guide pins.

 

[Matter]

What exactly do you mean by indexed correctly?

The socket has 2 slots with two guide channels at different levels. If you mean turn the bulb 180 degrees, and try to pit it in I thought 1157 bulbs could only go one way due to the offset nubs or guide pins.

It SHOULD go in only one way, but just be sure it looks correctly lined up with the bulb contacts. The pigtail inside the socket, make sure it is installed correctly in the socket.

 

[Banks]

[Waiting on Woodchuck...]

 

[Woodchuck]

I'm here, but it looks live everything that needed to be said already has..... lol.

 

[Carsala62]

Hello, I have a similar situation with my 70 Base:
* When head lights are off: all right turn signals work. Left front and back marker turn signal work except the main left back signal.
* When head lights are on: None of the turn signals work but the inside dashboard flashes.
I already replaced both flashers, the main turn signal switch and head light switch but it didn't help.
Can you please give an idea what the problem could be?
Thanks a lot!
Carsala

 

[Woodchuck]

Hello, I have a similar situation with my 70 Base:
* When head lights are off: all right turn signals work. Left front and back marker turn signal work except the main left back signal.
* When head lights are on: None of the turn signals work but the inside dashboard flashes.
I already replaced both flashers, the main turn signal switch and head light switch but it didn't help.
Can you please give an idea what the problem could be?
Thanks a lot!
Carsala

Are any of the bulbs LED?