polarity swap on front sidemarkers???

[724x4a/cchevy]

Has anyone else noticed that the polarity of the wires swap places when your headlights are on vs. turn signal blink??? Is this common with other trucks or just mine? I'm trying to work out an issue with my front LED sidemarkers. Thanks for the help!
Justin

[sneakysnake]

If the side marker blinks, then its a duel filiment bulb. one wire(park) comes on with the headlights, the other brighter comes on with the (signal) and they both share the same ground.Thats why when you lose the ground it makes your lights do weird things because it back feeds though the other filiments.

[clos69]

I agree with snake.....when you only have the turn signal on ...the front and side markers are in sych with each other..but when you turn your headlights on..they dance back and forth..it's common>

[Longhorn Man]

The side markers are NOT duel filiment bulbs. only the parking lights.
On the side markers, one wire goes to the parkng light circuit, and the other to the turn signal circuit. When there is no power to one of the wires, it becomes a ground.
So when the parking lights are on, the brown wire is hot, but there is no signal on the blue, making it ground. When you turn on the turn signal, you are putting 12 volts to the blue, so it is only a ground when the blue wire is not powered. So when the parking light up front lights up for directional light, the ground id lost on the side, causing it to turn off.
However, when the parking lights are off, the brown wire is a ground, thus, when the blue wire is powered with the turn signal, the light comes on WITH the front turn signal.

[724x4a/cchevy]

Originally Posted by Longhorn Man

The side markers are NOT duel filiment bulbs. only the parking lights.
On the side markers, one wire goes to the parkng light circuit, and the other to the turn signal circuit. When there is no power to one of the wires, it becomes a ground.
So when the parking lights are on, the brown wire is hot, but there is no signal on the blue, making it ground. When you turn on the turn signal, you are putting 12 volts to the blue, so it is only a ground when the blue wire is not powered. So when the parking light up front lights up for directional light, the ground id lost on the side, causing it to turn off.
However, when the parking lights are off, the brown wire is a ground, thus, when the blue wire is powered with the turn signal, the light comes on WITH the front turn signal.

So its as if they are swapping polarity right? It gives power to the light from different sides depending on headlights or turn signal and utilizes the non-powered wire as a "ground". Am i getting this right?
Justin

[JimKshortstep4x4]

Andy,

Great explanation on a circuit that seems to do funny things because of the way the bulb gets its "ground".

Jim

[Longhorn Man]

Justin, you are absolutly right.
And Jim, thank you very much. I've had to explain things like this to some real knuckleheads that couldn't figure out how to do ANYTHING and I have found a way to describe certian things where the average person (nonmechanic or even not mechanicly inclined) can understand it.

[FIVE 0]

So Justin, would the less draw from the led's that I put in cause my problem? Ill check the right marker wires for power as Longhorn has described then try regular bulbs from there to see If this corrects my problem.

[Longhorn Man]

whats it doing?

[FIVE 0]

I have led bulbs all the way around and an electric flasher. The rears and rear markers work correctly. The front left marker lights up when park lights are on and flashes. The front flashers light up when the park lights are on but dont flash. The front right marker does nothing at all.

[Longhorn Man]

Does it flash when you install a normal bulb?

[724x4a/cchevy]

We are trying to figure out how we can make LED front sidemarkers work. LED's are pickey with polarity and he has a situation with his truck that we have to resolve before i can make his front sidemarkers.
Justin

[FIVE 0]

Not sure. Im at work and will be checking things out in the morning. This topic came up when PMing Justin about some other lights and well Im learnin a thing or two. I was just thinking I had a ground problem or bulb problem and didnt think much of it because I had plans of changing to full led's. Now I think that my problem began when I added led bulbs to the front so Ill start there and see.

[Longhorn Man]

I don't know a whole lot about LEDs, however, i know they have a specific positive, and a specific ground... not reversable like a normal bulb. Knowing that, I would tend to think you wouldn't be able to do it like normal.
What you COULD do... on the CST/Cheyenne style lens, have the upper lens for parking light only, and the lower lens for directional only.
Some fairly basic harness mods would be needed... adding a ground on each circuit, ID'ing which wire is which on the 194 pigtail, then cutting off and hooking to the apropriate bank of LEDs.

[72lb4x4]

From Longhorn's description, and the way I see mine working, I'd think a bit of rewiring may be needed, and/or 2 sets of LEDs since you want to forward bias an LED to make it light.

There may also be differences in years vs the application since I think the early markers were wired differently than the later ones. I could be dreaming though.

[FIVE 0]

Longhorn, That is what brought us to where we are at. As I was visiting with Justin I learned that the front markers flash ( had the truck for almost 20 years and didnt know it ) Justin wires the fronts to have the upper on with park lights and lower on with signal. I wanted both on with park and dont care about signal. Main reason is I want the front to match the rear when park lights are on. So I will be first looking to see if I have a problem then looking to see if I can make what Im looking for work. Justin came up with plan B that has upper and lower but every other light come on with flasher.

Justin will be loosing money on this one by the time he has fielded all my questions. He's been very helpfull, as all I have found to be on this board.

[Longhorn Man]

Some trucks came with flashing ront markers, some did not. I have had 2 '70 chevy longhorns... one blinked, one did not. i did a poll on here 3 or 4 years ago and it is long lost in the archives, but there seemed to be NO continuity on why some did, and others didn't.
I think personally, with the 2 row lenses, I would just make them both steady burn.
But that's just me.

[724x4a/cchevy]

Yea, i think our best bet is doing a blend of the two like what i showed you. "plan B" Possibly even offset the reds/greens so they don't end up looking like columns.

[724x4a/cchevy]

I'm pretty sure the "polarity swap" is why your LED 194's aren't blinking. Flip them around in the socket and then hit the turn signals. 10% discount says they blink but won't come on with the headlights

[sneakysnake]

Originally Posted by Longhorn Man

I don't know a whole lot about LEDs, however, i know they have a specific positive, and a specific ground... not reversable like a normal bulb. Knowing that, I would tend to think you wouldn't be able to do it like normal.
What you COULD do... on the CST/Cheyenne style lens, have the upper lens for parking light only, and the lower lens for directional only.
Some fairly basic harness mods would be needed... adding a ground on each circuit, ID'ing which wire is which on the 194 pigtail, then cutting off and hooking to the apropriate bank of LEDs.

I guess I need to stick to (67's).LOL
I think your on the right track a normal ground is needed to make the LED's work.

[FIVE 0]

Well here is where Im at today.

I removed all led bulbs in the front and replaced with reg bulbs. I have a left signal and left blinking marker. I dont have any right signal but lights on with park. I tried new bulbs, even though the one looked fine. Tried new housing grounded and still no blinky. However replaced side markers with led bulbs again and they work and left one blinks. And yes it does matter what way they are inserted. Rears still work correctly. Didnt have time to replace them to see if that would cure the right front blinking problem, not sure if it would be worth the time. At this point Im thinking it may be somthing else. When I have a few min Ill do some wire checking. Any other thoughts?

BTW Justin, Check is in the mail