2016 Suburban LT Fog Lamps install with OEM switch

[GusSanchez300]

nice write up for ppl trying to do the same!

 

[Bxbound7595]

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

Preface
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.

Wiring

Headlamp switch
Fog lamp request wire (Blue/Gray)



BCM
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!



Underhood
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



Appendix
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

 

[Bxbound7595]

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

Preface
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.

Wiring

Headlamp switch
Fog lamp request wire (Blue/Gray)



BCM
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!



Underhood
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



Appendix
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

Can do the same to a 2015 suburban

 

[chadman123]

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

Preface
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.

Wiring

Headlamp switch
Fog lamp request wire (Blue/Gray)



BCM
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!



Underhood
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



Appendix
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

. I do have a quick question. We were able to hook the 611t up but could not figure out how to hook the harness up under the hood. Seems like we had a few more wires. Do you have any additional pics or tips on that process? Or if anyone else has hooked up these lights?

Thanks

 

[Josh61513]

Has anyone tried to have the dealer flash their BCM to add the foglights to the BCM? I would like to add the factory fogs to my LT but I'd like replicate the factory setup even further if it's reasonably possible.

 

[nilleo]

Has anyone tried to have the dealer flash their BCM to add the foglights to the BCM? I would like to add the factory fogs to my LT but I'd like replicate the factory setup even further if it's reasonably possible.

On top of a BCM flash, you're also going to need a new engine harness and fusebox if you want the full "stock" functionality. A more cost-effective solution that could appear to be stock would be if someone could "sniff" out the CAN messages to the instrument cluster that cause the cluster to show that the lights are on (if there's even an indicator on the screen for it). With those messages - we could put something together the fool the cluster into thinking that the BCM is sending all the right information when we turn the fog lights on through these other methods and update the screen accordingly (again, assuming there's even any sort of indicator on a stock Suburban/Tahoe with fog lamps).

 

[Josh61513]

Good point.

But if the pins are available to add a wire to the output of the fusebox couldn't a wire be added outside of the bundle from the fusebox down to the fog lights themselves? I've seen a link somewhere in another thread that was for an 07-13 silverado fog light harness for cheap. Same fogs & connectors are used on these trucks. That wouldn't be so bad.

 

[nilleo]

The pin is missing both at the harness that plugs into the fusebox and goes out to the lights, and it's also missing from the fusebox internals as well - so if you pin it into the harness, there's still nothing for it to mate to at the fusebox board internally. During this install, I took the fusebox assembly apart to see what I could do to fit it as close to stock as possible on the cheap.

 

[Josh61513]

I have no idea what the inside of a fusebox looks like, but based on your comments it sounds unrealistic to add whatever is needed to connect the wire from BCM to a relay and supply +12V to the input of the fuse?

I can't believe GM uses unique fuseboxes based on options. I would have expected the fuse for fogs to just be missing, and maybe to omit the wiring from the fusebox to the fog location. Maybe it has to do with safety/error-proofing somehow, I supposed leaving a fuse out isn't error-proof.

So the only benefit of flashing the BCM would be to enable a fog light indicator on the dash, if there is one?

 

[nilleo]

Yea, I was really surprised they'd bother equipping different fuseboxes on the trucks, I would think that it would be more scale economics to them to supply the same fusebox.