GM Upfitter go to guy

Mark57 · December 7, 2023

I have a question for a person that knows his way around a electrical question. Can you please message me. Thank you Mark

redwngr · December 10, 2023

Post your question so everyone can benefit.

Mark57 · December 10, 2023

I have a 2024 1500 reg cab/short bed pro, the truck did not have fog lights. I bought aftermarket lamps for the spot below the bumper, got a dash switch with the fog light button the only difference I see is cargo fwd facing spotlights in my side mirrior are in a different location on new switch. I pulled my switch out of dash and there are 2 open spaces on my plug. What I need are the plug wiring locations for a 2024 1500 pro and what they are for with no fogs to see the oriantation to swich, and one for a 2021 1500 with fogs (the switch I bought) so I might be able to compare repin to make it work. I will not be buying a OEM harmess and I wont be refashing my BCM. If its posible finding out what that postion for fog lights in the new switch can be used as a Grn-Pos- or trigger for my relay. I hope what I want to do is understandable with this post. Thanks Mark

Bikerjon · December 11, 2023

2024 1500 Reg. cab. What trim LT, Custom? Are you trying to use the switch assembly below the center section?

GETGONE · December 11, 2023

You can't make the OEM switch work without reprogramming the BCM. The dealer won't do it without it being a GM accessory kit either. My dealer won't even do the program because I didn't buy the kit from them, even though it is a GM Accessory kit with the programming authorization code.

There's a whole wiring harness that goes between the light switch and the fogs you need as well. I have mine using a diode jumper from the parking light circuit so that it triggers the relay for the fogs.

Mark57 · December 11, 2023

Thanks for the rely guys. My truck is a Pro trim and Like I said I was not going to do the BCM and without doing the BCM a harness would be a waste of money. And knowing that because my truck did not come with that option. All switch's controls a circuit whether it be a signal for a relay with a pos or neg, all I need is the reference in upfitter to verify the pins in there locations for the functions they do. I have read here people want to use the 4 gang AUX switches to control other things so what I want to do I believe is no different then that. When I was waiting for my truck to get in I went through the entire mod section and got some good ideas from some of the posts of people doing things to there trucks that were pretty cool that's why I ask I thought there might be that one or two guys that might be able to help me figure this out. Thanks Mark

Edited December 11, 2023 by Mark57

gemarsh · December 11, 2023

I know this is for the 2500/3500. I am assuming the headlight switch would work the same as a 1500.

The switch is not a normal trigger switch (+/-). It uses different resistance values for functions, relayed to the bcm.

I'm including a screenshot of the upfitters body building page...

newdude · December 11, 2023

5 hours ago, Mark57 said:

Thanks for the rely guys. My truck is a Pro trim and Like I said I was not going to do the BCM and without doing the BCM a harness would be a waste of money. And knowing that because my truck did not come with that option. All switch's controls a circuit whether it be a signal for a relay with a pos or neg, all I need is the reference in upfitter to verify the pins in there locations for the functions they do. I have read here people want to use the 4 gang AUX switches to control other things so what I want to do I believe is no different then that. When I was waiting for my truck to get in I went through the entire mod section and got some good ideas from some of the posts of people doing things to there trucks that were pretty cool that's why I ask I thought there might be that one or two guys that might be able to help me figure this out. Thanks Mark

The headlamp switch has no direct control over the lighting per say. Its just a command switch to the BCM and then the BCM to the LCM.

GM has no official fog light upgrade path for the refresh 1500 trucks still. They were working on one but appear to have abandoned it all together.

On 19-24 trucks the other issue with trying to do what you are hoping you can, is that all of the lighting is operated via a lighting control module as well. If the LCM gets pissed off, it can cause all sorts of hell.

Headlight switch tells the BCM what it wants the lights to do so if you leave it in AUTO, it tells the BCM run the lights in AUTO, then the BCM tells the LCM to operate the lights accordingly. Fogs are operated the same way and via the BCM and LCM.

So your only OEM route for operating them, aside from some sort of aftermarket switch installed somewhere and find some sort of powered circuit and a ground, is the factory Upfitter switch package.

Here's the instructions for that package - UI-Bulletin-193b.pdf (gmupfitter.com)

On a 2024 Sierra Pro, that has the old dash still so the kits are available for it. 84942073 is for black interior, 84942074 is for the dark atmosphere.

64BAwagon · December 11, 2023

I wouldnt look for a lot of work to come out on existing trucks. GM has their hands full with this latest architecture and the 27's are rumored to be another big step.

Mark57 · December 12, 2023

Ok thanks for all the input, looks like I will forget using the headlight switch route and going with the upfitter switch's. Problem is when I put in 2024 1500 pro 2.7 nothing will work with that setup. I also want just the 3 button so do I just cut knee bolster and get the plug for the back and wire in relays like I saw in a search for upfitter switches. On another note my truck has space for another 3 gang switch pack below my radio next to cargo lights and start stop switches, can that be wired for the fog lights it shows 2wd 4wd on switches part number 86827805. Hope this is not a dumb question just asking. Thanks Mark

Edited December 12, 2023 by Mark57

Mark57 · December 12, 2023

Did some more reading about getting a 3 pack next to my existing switches so that wont work. So back to getting back to cutting and installing a 3 gang upfitter switch pack in my knee bolster since they do not offer a new bolster with it cut for a 3 switch in my configuration. Thanks Mark

gemarsh · December 12, 2023

27 minutes ago, Mark57 said:

Did some more reading about getting a 3 pack next to my existing switches so that wont work. So back to getting back to cutting and installing a 3 gang upfitter switch pack in my knee bolster since they do not offer a new bolster with it cut for a 3 switch in my configuration. Thanks Mark

Do you have a link for the 3 gang switch assembly? Did not know there was that option. All I have installed/seen/came oem, were the 5 gang switch assembly.

Mark57 · December 12, 2023

Looks like 84938259

Bikerjon · December 15, 2023

On 12/12/2023 at 5:29 AM, Mark57 said:

Ok thanks for all the input, looks like I will forget using the headlight switch route and going with the upfitter switch's. Problem is when I put in 2024 1500 pro 2.7 nothing will work with that setup. I also want just the 3 button so do I just cut knee bolster and get the plug for the back and wire in relays like I saw in a search for upfitter switches. On another note my truck has space for another 3 gang switch pack below my radio next to cargo lights and start stop switches, can that be wired for the fog lights it shows 2wd 4wd on switches part number 86827805. Hope this is not a dumb question just asking. Thanks Mark

You could check Gen5 DIY. They have wiring kits that connect into the front marker lights or the headlights. I don't know if they have kits for 2024s.