Should I have 5 volts in turn signal circuit?

[siggyfreud]

Hey all,

Trying to diagnose and fix issues with new headlights I've installed. I have another thread about the headlights, but I in doing so I have a general question.

With my turn signals off, but park lights on, should I be seeing 5.5 volts in the turn signal circuit?

If I pull wiring from a front turn signal or side marker and put the park lights on, the park light wire reads 12v as expected. However, the turn signal wire reads 5.5v at the same time. Is this normal?

Cheers all.

[truckster]

There shouldn't be any voltage there. Check your grounds; you've probably got a circuit grounding through the turn signal circuit.

[siggyfreud]

Would make sense if it was the park light circuit then right, since that voltage only shows up when that's on?

[truckster]

That's what I would suspect.

[siggyfreud]

I have found that if I pull the front driver's side park lightbulb out, the circuit voltage drops to 0. Does that mean I need to ground that light better, and if so, how do I go about that since it's only two wires, and both are power?

[Steeveedee]

I recall there is something about that circuit that causes the side marker and the turn signal part of the parking lamp to alternate bright/dim when the turn signals are used, but doggone if I can remember the details. It does look like you are missing a ground, though. My guess is to check the park/turn signal lamp socket and ground.

[cj847]

Originally Posted by siggyfreud

I have found that if I pull the front driver's side park lightbulb out, the circuit voltage drops to 0. Does that mean I need to ground that light better, and if so, how do I go about that since it's only two wires, and both are power?

I'm no expert, but the light socket grounds against the housing. When you pull it out it interrupts the circuit, hence volts=0. Check that the socket is getting good ground as you are reinstalling as they can get bent.

The power to the blinkers usually go thru the flasher to make them blink. However, I am not sure if a flasher is bad do you get a light continuous or a "no light" condition.

The parking light bulb is dual filament. One is parking, the other is blinker. They are separate circuits.

[siggyfreud]

I'm just not sure how to better ground it. The housing appears to be plastic, so I'm not sure where I'd run an additional ground. I could try grounding at the rear where the housing is metal though. Think that might work?

[Steeveedee]

Take a look at the other side to see what is different, since it works properly (right?). Maybe that will help.

[truckster]

Originally Posted by siggyfreud

I'm just not sure how to better ground it. The housing appears to be plastic, so I'm not sure where I'd run an additional ground. I could try grounding at the rear where the housing is metal though. Think that might work?

If you're talking about the turn signal/park light in the front bumper, the housing should be metal. It grounds through its attachment point to the bumper (the bumper is grounded to the frame).

[siggyfreud]

There are no turn signals in this front bumper. It's custom. I'm talking about the turn signals in the side markers on the front. Those appear to be plastic housings.

[70STOVEBOLT]

Originally Posted by siggyfreud

There are no turn signals in this front bumper. It's custom. I'm talking about the turn signals in the side markers on the front. Those appear to be plastic housings.

They are plastic. There should be a ground wire coming out of the front lighting harness that grounds to the core support by the voltage regulator.

[siggyfreud]

Originally Posted by 70STOVEBOLT

They are plastic. There should be a ground wire coming out of the front lighting harness that grounds to the core support by the voltage regulator.

Okay, I'll take a look for that. Thanks all for the assist!

[truckster]

Someone correct me if I'm wrong, but I don't think the marker lamps had turn signals in them. They have two wires; one is hot with the switch on and the other is ground. If your signal lamps are wired into your marker light, that might be your problem.

[siggyfreud]

Originally Posted by truckster

Someone correct me if I'm wrong, but I don't think the marker lamps had turn signals in them. They have two wires; one is hot with the switch on and the other is ground. If your signal lamps are wired into your marker light, that might be your problem.

Wouldn't surprise me if that's the case, but wiring to them does look factory.

[70STOVEBOLT]

I think 72 only wiring harnesses were set up to make the side markers blink with the turn signals.