Welcome to the Nation.

I think that you are the first to ever ask about that. I don't know the reason for it, but there are only two wires to the socket, so my guess is that only one filament is used.

 

Wow, on here my first day and already have a scammer trying to sell me something!

 

Yeah, we've been getting a lot of trash here lately. Notice that they just joined.

 

That bulb is brighter on day lamp use, dimmer on parking light selection, thus 2 elements.

 

I cannot get the second filament to light putting the vehicle in gear during the day.

 

There are only two wires to the socket, one power and one ground. How do they switch power to the second element in the bulb?

 

I noticed that as well when putting in new headlight housing and switching to LED. Badland Industries has a YouTube video explaining a number of light-related mods on these trucks, and making both running lights flash with the turn signal is one of them. It does require a new socket (one w/ four wires), but I think they should have come from the factory that way.

 

I first noticed it when I pulled up to a large window: With the DRL on, notice that bulb's intensity, turn your lights off, bulb goes out, turn on parking lamps, note that bulb shines dimmer. Must be something in the circuitry.

 

You have a 2005. Aren't your DRLs the parking lights, not the headlights?

 

Yes, indeed.

 

Digging up an old thread, but the way these are wired is the outside bulb is turn/marker and the inside bulb is just marker (or in your case, DRL/marker). They're daisy chained, so you have one signal lead that goes from the plug to that outside socket, but the marker lead goes from the plug to the outside socket then to the inside socket. Ground does the same, plug to outside then to inside.

I'm trying to find info on that inside bulb socket so I can replace it with a three-wire for a mod of my own :-/

 

Badland Industries has a youtube video (link below) talking about various light mods. This is one of them. I believe it uses the same bulb and socket, you just need a socket with another wire to tap into the other turn signal. I believe he has a link to what he uses in the description of his video.

 

Badland Industries has a youtube video (link below) talking about various light mods. This is one of them. I believe it uses the same bulb and socket, you just need a socket with another wire to tap into the other turn signal. I believe he has a link to what he uses in the description of his video.

My thread is over here with a picture of what I'm looking for.

3157 socket info

I've got a recently acquired 2010 Colorado that I'm doing a bunch of lighting updates to. I'm running into a challenge though, I'm trying to setup dual signal lights, and need to update the socket from the marker-only socket to a standard high-low type socket. The problem is, in their...

www.355nation.net

I watched his video, and he's doing something similar to me, however he said in his video description that the socket he got (I think it's actually the same as the one I got) didn't work and he had to modify it... which is probably exactly what I'm going to have to do.

I'm doing the dual brake light mod he's doing, I'd seen that video before, but I couldn't find it again when I went looking for it and had to start from scratch, lol. Thanks for sharing, I'll actually save it this time :-D Difference is, I'm using switchback LEDs in the backup light spot so I can use it for both signal and reverse.