2016 Suburban LT Fog Lamps install with OEM switch

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TYF Newbie
Jan 19, 2021
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Ryan - can I ask what brand fog lights you went with? I am talking to Matt about his harness and wanted to see if you recommended the lights you went with.



I'd also like to add my name to the recommended list.
I also HIGHLY recommend Matt's Kit!
The videos, the 28 minute one and Matt's extra instructions via email, guided me though the harness wiring from the lights to the junction/fuse box under the hood, as well as inside the cabin.
He broke every step down to where I could understand it and follow along....I had no clue, but I've learned a lot by doing this.

My vehicle: 2020 Tahoe LT. No pre-wires from factory...just those plastic covers where the lights go.
Aside: I did initially go to a local custom shop where the lights were installed....but their wiring, though not "invasive", was sub-par, putting it nicely, and were wired to the headlights, uncontrollable.
Thankfully, was able to remove what was done...no factory damaged components...After watching Matt's videos, I decided I could do it...

I wired mine the exact same way as Michael, similar issue...needed to have taken apart more components on that right side...But the left side was super simple. Harness from fusebox went virtually straight down to where the harness to the lights were....on the driver side.

Had to run power from the side panel area down to the cabin junction box, because of what was present from the factory.
Matt's instructions made all this super simple....and I really don't like messing with wires:)...but was easy to do.
It took me about 4 hours, BUT I have only basic tools and I wanted to go very slow and easy, plus 49yrs old eyes:)...but a most methodical process...I didn't see that time passing...was a great project!

Same thing:
No routing through to the engine bay!!
Factory like install, yes, utilizing the OEM switch!!...this is what I was hoping to be about to do.

Anybody looking to do this...you can and it looks great...I can't tell that it's not from the factory!!
Super worth the investment!!

Sorry that I don't have a before pic...but posting my after pic.

Big Thanks Matt!
Ryan Beard

View attachment 262273

Robert Gardner

TYF Newbie
Mar 2, 2021
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Hey all,

I wasn't able to find many (or any) cases where aftermarket fog lamps were added to a 2015+ Suburban /Tahoe (or similar generation) with the OEM switch, so I created an account here to share for anyone else that's interested.

Let's get to it…

Tools you'll need:
7mm socket driver
10mm socket driver
T15 torx driver

Suggested tools:
Clip removal tool
Electrical tape
Wire ties

Parts used:
Spyder FL-CTAH15-C fog lamp kit
GM headlamp switch w/fog part# 22752195
DEI 611T

I was hoping to use as much factory wiring for this installation as possible to keep everything as “factory” as possible, but mostly to avoid doing more work than I had to :). I dug into some schematics to see what the factory wiring was like and then proceeded to look for all the wires in the truck before getting dirty.

The good news – the factory fog lamp fuse was installed in the fusebox from the factory, woohoo. Also, the wire from the headlamp switch harness to the BCM was present at the headlight switch and at the BCM. The wire from the BCM to the underhood fuse box for the OE fog lamp relay trigger was also present at both the BCM and the underhood fuse box, excellent!

The bad news – the wires that are supposed to go from the fusebox to the factory fog lamps weren't in the wire bundle going to the front grille where they're supposed to be. I investigated further and found that the wire isn't even pinned in at the fusebox, way to cheap out GM!

Here's where the wire should go, notice how pins are populated to the left and right of the pin we need, but not where we want one :(


This setback meant that I would have to run my own wiring from the aftermarket fog lamps to the battery, and a relay to to control it all. I'll still be using the factory trigger wire for the factory fog lamp relay and just use that to trigger my relay.

Reverse engineering
The factory front fog lamp circuit works as follows – when you press and release the fog lamp request button at the headlamp switch, this sends a ground pulse to the BCM. The BCM interprets this pulse as a request to turn the fog lamps on, and if the headlamps are on, it sends a ground signal to the underhood fusebox to the fog lamp relay. When the fog lamp relay clicks on, it sends power to the front fog lamps and there ya have it.

Since I don't have access to a programming tool to enable the fog lamps feature on the BCM, it didn't do anything when I installed the new switch, as expected. No matter, I brought the 611T into the picture to replace the BCM's role in this party. So the 611T will take the momentary pulse from the fog lamp switch and control a latching on/off ground output that I will feed into the factory fog lamp relay wiring. Since the factory fog lamp relay wiring is missing at the fusebox and I'll be using my own relay, I'm pretty much just hijacking this wire as a way to get through the firewall without running any new wiring.

611T wiring
Black – to BCM brown connector, Blue - pin 22
Green – to headlamp switch, Blue/Gray – pin 6
Red – to BCM brown connector, Red/White – pin 4
Yellow – to BCM brown connector, Blue – pin 22
Brown – to BCM brown connector, Brown – pin 10

611T wiring explained
The module is “active” when the Black wire is at ground and the Red wire is at 12V+. I wired it up so that it only has ground when the parking lamps are active so that the fog lamps can only come on when the parking lamps are on, and turn off when the parking lamps turn off. The Green wire receives the momentary pulse from the headlamp switch to control the MOSFET that the Yellow and Brown wires go to. The Yellow wire is looped over to the Black wire so that it only has a ground input when the parking lamps are on as well. Lastly the Brown wire is what will trigger the aftermarket fog lamp relay on/off witch each press of the fog lamp switch when the parking lamps are on.

Interior Disassembly
Remove the fuse panel lid on the left side of the dashboard – it's the large plastic panel covering the interior fuses on the left dash.
With that door off, remove two T15 torx screws from the side of the lower dash panel as shown.


Next, remove another two T15 torx screws holding the lower dash panel from underneath, they should be easily visible.


Optional – use a small flathead screwdriver to unclip the hood release latch and separate it from the panel. You don't have to do this, but doing so will let you completely set that panel aside once you unclip it from the rest of the dash assembly.

You should now be able to unclip the lower dash panel. There are about 3-4 clips holding it on now, just get a good grip and pull towards the rear of the truck. These clips can be stubburn.

Once you take off that lower dash panel, you should now see two 7mm bolts holding the switch panel in place. Take those bolts off and pull that panel off – again, pull toward the rear. There are maybe two or so clips on this one. Unplug the harnesses and swap out your switch then set the whole thing aside.


The switch is held on with these clips...


Exterior Disassembly
Start the engine and turn the wheels all the way to one side.
Remove the 7mm bolts securing the felt wheel-well cover on the front bumper.


Get under the bumper and remove two 10mm bolts and a clip holding the felt cover on from each side of the truck.


Reach in and remove four 10mm bolts holding on the fog lamp blanks. (the left-most screw is out of view in the image below due to the angle)


Put the new fog lamps on, turn your wiring up through the fender and into the hood area, and put it all back together if you'd like. Don't forget to secure the wiring with a few wire ties to keep everything tidy.


Headlamp switch
Fog lamp request wire (Blue/Gray)


X5 connector with parking lamp (Blue) and fog lamp (Brown) relay activation wires and a decent constant 12V+ source (Red/White) for the 611T note: the fog lamp relay wire may be Brown or Brown/White, take note of which color it is for you!


Trigger wire for your fog lamp relay, should be the same color as you found inside at the BCM


Just in case it's not exactly clear from the previous picture where that harness is, here's a more zoomed out shot...


Good 12V+ source for your fog lamp relay


For your reference, here's a rough block schematic of some of the circuits discussed here.


And lastly the final product

All lamps on


Parking lamps and fog lamps only


Fog lamps off

Whre are you located wana do another one lol


TYF Newbie
Jan 25, 2022
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Victoria TX
2020 Tahoe LT. Upon review of this thread, I'm in the same situation. Lights are installed and working, but the mickey mouse switch has to go! I ordered the OEM headlight switch (84448511) and a recommended connector kit (19329741). It appears this connector kit is possibly not required. Before I r&r the switch, any comments or advice will be most appreciated. IMG_2382.JPG


TYF Newbie
Jan 25, 2022
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Hey all - I have a 2019 Tahoe LT that did not come with factory fog lights. My plan was to install some - and after researching I decided I wanted to be able to control them separately from the headlights (so that eliminated the Gen5diy kit - that only allows your aftermarket fogs to be turned on with the headlights). I also did not want some funky looking after-market switch connected under the dash, or stick-taped to anything so I did some digging into cmatt's solution. Matt had me check some factory wiring to determine if I could use his kit on my vehicle. A couple of the wires did not match up to what Matt had in his diagrams, so after some emails back and forth with him it was theorized that I had a "fleet" vehicle. A quick check of the code in the door jam/VIN confirmed this. Matt had me test for voltage at other wires and after reporting back he said "no problem - I got you covered!" I ordered his harness and a set of LED fogs from CARID (https://www.carid.com/2019-chevy-tahoe-fog-lights/lumen-projector-led-fog-lights-1233543783.html) and away I went. Getting the actual lights installed was super easy, trying to find a way to run the wire from the junction box under the hood to the fogs proved to be difficult, at least different, from what I was expecting.

Matt's directions were to run the wire from the junction box (see "c" in my photo below), along the hood release cable, across the top of the frame over the radiator, down the side of the passenger headlight (see "b" on the photo" connecting the lead from the junction box to the harness that connected to both fog lights under the vehicle. On my Tahoe I could not find a good path on that side of the engine bay to run the wire and I was not able to remove the grill to run the wire - at point "a" on the picture the grill appeared attached to the bumper in a way that I could not separate the two - so I set off to find another path.
View attachment 234002

Point "c" shows the junction box, so after following Matt's INCREDIBLY detailed instructions on how to access the box, and add the necessary wire, I found a path through hole with the upper arrow. You can see the same wire where the lower arrow points. This put the connection directly at the driver's side behind the newly installed fog lights.

View attachment 234003
I swapped the connection between the two fogs so the wire from the junction box could now be connected on the driver's side. Now at this point, the fog lights are in, and wired to the junction box.

Matt provided me with a link to a really good deal on ebay for an OEM headlight switch WITH factory fog lights - so I swapped that, and wired the rest of his harness per his instructions and videos. At one point I got stuck and could not locate a connector Matt referred to in his instructions - so I reached out and he responded with another picture, and video to help me out. After that I was all wired up - a quick test revealed everything was working PERFECTLY.

A couple of notes with the way this worked in my Tahoe:
  • there is no fog light indicator on the dashboard that comes on when you turn the lights on and off - no big deal, you can tell they're on
  • I can turn the fog lights on no matter what the headlights are doing. On, off, brights, parking lamps, it does not matter I have complete control over the fog lights -through the OEM switch.
  • Matt's kit does NOT require running any wires from the cabin to the engine bay
  • Matt's kit utilizes the factory fuse for the fog lights
  • the relay box that Matt provides needs to be "secured" to something under the dash. I ended up using velcro tape and attaching it to the back of the BCM to keep it out of the way
  • NO FACTORY WIRES WERE HARMED IN THE INSTALLATION OF THESE LIGHTS AND MATT'S KIT! Everything can easily be undone, and what's better the install looks mostly OEM anyway!
Photo of before:
View attachment 234004
Photo of after:
View attachment 234005

All in all - I am VERY pleased with the look, the investment (time AND money) and the support/help Matt provided. If you're thinking about doing it - do it - I HIGHLY recommend his kit!
How are the lights holding up for you? I just got a hold of Matt and I'm looking to do the exact same set up as you.

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