Why don't my turn signals alternate between the side marker and the parking light?

[Barrera92]

I noticed that when I use my turn signal all three bulbs (2 for the forward facing parking light and 1 for the corner/side marker) flash at the same time. Every other truck Ive seen alternates between the two with one flashing first then the other. Does any one know why this is? I linked a video of my turn signal to demonstrate what I mean.

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[Fuzzy]

They only alternate when headlights/parking lights are turned on.

 

[someotherguy]

This ^^ confirmed

Richard

 

[88GMCtruck]

That is correct. The reasoning behind this is the corner light is single filament and uses what I call a floating ground. The two wires to the light are the signal and the parking light circuit, both have 12V when on. So when you have the parking lights on, and you signal, it turns the light off when the bright filament of the main parking light is on, creating the alternation. Both wires have 12v at this time and thus the bulb is off. When the parking lights are off it and the signal is turned on, the it gets 12V and uses the parking lights circuit that is not currently energized as a ground, thus flashing at the time time.

 

[Barrera92]

Wow. I really didn't think of that. Thanks for clearing it up for me.

 

[Steve352]

That is correct. The reasoning behind this is the corner light is single filament and uses what I call a floating ground. The two wires to the light are the signal and the parking light circuit, both have 12V when on. So when you have the parking lights on, and you signal, it turns the light off when the bright filament of the main parking light is on, creating the alternation. Both wires have 12v at this time and thus the bulb is off. When the parking lights are off it and the signal is turned on, the it gets 12V and uses the parking lights circuit that is not currently energized as a ground, thus flashing at the time time.

So simply put, how would I make them all blink at the same time ALL the time

 

[88GMCtruck]

So simply put, how would I make them all blink at the same time ALL the time

You would need to do one of two things:

Wire the side like as ONLY a signal. It would not be on while the parking lights are on.

OR

Wire in a 2-filament bulb, or a second bulb.

 

[Steve352]

Thanks

You would need to do one of two things:

Wire the side like as ONLY a signal. It would not be on while the parking lights are on.

OR

Wire in a 2-filament bulb, or a second bulb.

I think I’ll just keep it factory. Lol

 

[HotWheelsBurban]

When doing the upper corner lighting mod, will this change anything about how this works? Doesn't sound like it would, but I would like to hear from those who have done this mod. I really like the alternating lights; it seems like it would catch people's attention when they saw it. And since that's what turn signals and emergency flashers are supposed to do... I'd like to keep that function. Several times during the week, we have to be parked in the street, loading or unloading, and even though people SHOULD be able to see 21' of big Chevy truck, the more lighting is on it, that should help. And with the pickup, the tailgate doesn't block the taillights like the barn doors do on the Burb....