Adding aftermarket fog lights - want them on with headlights

[Kev2lee]

9 hours ago, GETGONE said:

Yeah, I pulled the brown wire from where GM instructions tell you to put it and I used a T tap to tap the parking light wire under the dash. That's the only thing you need to do. Leave everything else alone as the GM instructions state. The BCM is what needs an output where GM has you put it on the connector and the input is the foglight switch that comes with the kit. I never did change back to the original headlight switch. I'd have to look to see what wire and connector the parking light is if you don't already know.

 

Thanks for the reply, appreciate it!

Just a couple questions to clarify, if you don’t mind:

1) So you ran the wire (Brown) that came with the OEM kit, to the UEC and plugged it in to B3 (fuse box under the hood).

 

2) From the UEC you ran it to the BCM, Slot 10.

 

3) Once plugged into slot 10, you used a T-tap to tap into the parking lights.

 

Just want to make sure I’m following correctly. New at auto electrical.

 

Im not sure which wire is the parking lights. I’ve read that it’s a blue wire but I don’t have a blue wire. I’m sure I can figure out which one it is with some more searching. 

[GETGONE]

What year is your truck? I unplugged the wire from slot 10 in the BCM once I found out they wanted $200 to program it, then later told me they wouldn't program it because I didn't buy the kit from them. I took that wire that would have went into slot 10 and T tapped it into the parking light wire.

[Kev2lee]

On 11/9/2025 at 8:27 PM, GETGONE said:

What year is your truck? I unplugged the wire from slot 10 in the BCM once I found out they wanted $200 to program it, then later told me they wouldn't program it because I didn't buy the kit from them. I took that wire that would have went into slot 10 and T tapped it into the parking light wire.

 

I have a 2019 custom (new body). 
Yeah, I went to two different dealers. One had to make 5 calls to figure out how to install them and told me $200 to flash the BCM. The other dealer told me $200 as well. That was a hard pass after purchasing them and doing the install myself.

Thanks again for your help, I’ve had them installed for almost 3 years now and never got them to work. Just need to figure out which wire is the parking lights!

 

[Kev2lee]

On 11/9/2025 at 8:27 PM, GETGONE said:

What year is your truck? I unplugged the wire from slot 10 in the BCM once I found out they wanted $200 to program it, then later told me they wouldn't program it because I didn't buy the kit from them. I took that wire that would have went into slot 10 and T tapped it into the parking light wire.

Hey,

just wanted to let you know that your directions worked perfectly and I appreciate the help!!!

[GETGONE]

Good deal! I forgot to come back to this post. I uninstalled my bypass resistors when I took the truck in for the 6.2 engine recall so they couldn't claim there were issues I caused. I looked at the Boost Auto instructions when I made new resistor harnesses and found they make their setup the opposite of what I thought. On theirs they say the blue ring toward whatever side. I assumed they were using the ring on the diode to match up with the blue shrink wrap ring they put on the resistor. It's not, it's on the OPPOSITE end. I had built mine with a blue shrink wrap ring on the same end as the diode ring. When I installed them they didn't work as expected. Luckily with the T taps I used I could just unplug and swap ends and then everything worked as expected. Turns out I didn't remove the fog light wire in the brown BCM plug. I just left it there and T tapped it to the parking light wire. Doing this also keeps your fogs on when your high beams are on, unlike factory, where it turns the fogs off when high beams are on.