Low power at taillights

[Dahlenchris]

07 signature limited. At the taillights, using a voltmeter, the driver side is showing 0.50 volts. The pass. Side is normal 12 v. Is there a fuse i should chasing down or what? Ps- I've had LED bulbs in all 4 spots & never had issues until now.
Thank you.
Chris

 

[Action]

The driver's side may have a poor ground

Action

 

[G-370077]

The driver's side may have a poor ground

Action

Cant remember which wire. One was 0.5v, another pin had 12v. But I'll try to track the ground. Thanks

 

[Dahlenchris]

Thanks. One pin was 0.50v, another had 12v.

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[HighwayStar]

Thanks. One pin was 0.50v, another had 12v.

I'm confused, are you saying this is solved?

 

[Dahlenchris]

I'm confused, are you saying this is solved?

No. I'll have look again and take note wire colors. When parking lights are on. The led bulb has maybe 4 diodes lit. But there is no visible parking, turn signal or brake light. Just on the drivers side, the passenger side is all good. Now to figure out where the ground is connected.

 

[Action]

Typically the ground wire attachment to the body will be close to the lamp assembly.

Action

 

[Dahlenchris]

Thanks

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[HighwayStar]

No. I'll have look again and take note wire colors. When parking lights are on. The led bulb has maybe 4 diodes lit. But there is no visible parking, turn signal or brake light. Just on the drivers side, the passenger side is all good. Now to figure out where the ground is connected.

Ok, I have an 06 Signature L and the wiring diagram for the 06 model, so presumably the same.

For the rear lamb assembly connector, I am seeing 3 pins in the plug, is that what you see?
Second, when you are measuring voltage, could you describe exactly between what you are measuring the 0.5V and the 12v? Is it between 2 pins in that connector? Between the pins and an external ground, such as an unpainted chassis bolt?

 

[Dahlenchris]

3 pins. I was using the ground pin in the connection. When it stops raining, I'll open it up to see which wire was .5v and then try grounding it on the body.

 

[Action]

On a 2 filament bulb, there will be 3 wires.
One for tail light hot
One for brake/turn signal hot
One for ground.

Since the ground side is connected at the bulb, if the ground wire in the harness is not well connected, the brake/turn signal circuit will attempt to find a ground in the tail light circuit. Or the opposite will happen if the ground is poor.

Action

 

[Dahlenchris]

Thanks. Im in Iowa, 2 days ago, short sleeve weather, today ice on the car 🙂. I'll wait for a "heat wave" to mess with it.

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[Norms1stTC]

LED is the problem

 

[Dahlenchris]

LED is the problem

I've had led since i got the car 6 months ago. Also the passenger side has no issues.

 

[HighwayStar]

I'm not sure how the LED could be the issue if incorrect voltage is being seen at the plug with no bulb attached, unless running LEDs has damaged another part of the circuit.

On a 2 filament bulb, there will be 3 wires.
One for tail light hot
One for brake/turn signal hot
One for ground.

Since the ground side is connected at the bulb, if the ground wire in the harness is not well connected, the brake/turn signal circuit will attempt to find a ground in the tail light circuit. Or the opposite will happen if the ground is poor.

Action

This makes sense to me. Checking relative to chassis ground should show one pin with +12v, one with +12v when the turn signal is on, 0v otherwise, and one with 0v for ground.
Checking the quality of the ground is another matter if the fault is intermintant.