2016 Suburban LT Fog Lamps install with OEM switch

[87nokturnal]

Has anybody here tried the plug and play harness for the fog light installation from Gen5diy?

 

[Tk59194]

This guy did

 

[kurt1305]

My only concern with the Gen5diy harness is that it appears to have no fuse. Does anyone else share this concern?

 

[Po-B0b Auto Tech]

Guys, great thread. I've got a '17 LT and am amassing parts and research info to do this installation. Couple of questions:

- Does anyone know precisely where the factory front fog lamp relay (KR46 in the schematics) is located in the underhood fuse block (schematics all say it's in there)? Could it be one of the upfit relays that's dedicated to the T3U option? Yeah, I looked in my Owner's manual, chatted online with GM, and called 4 Chevy, GMC and Cadillac dealers. The location of this relay must be some huge state secret - even looking at OMs from '15 on, there's no mention of it and no one I've talked to can answer the question.

- When bypassing the BCM, using the 611T and BYO relay, do the fog lights remain on when high beams are on? Pretty sure that would fail inspection in VA (and probably other states). If they do stay on, is there a way to provide a trigger when EITHER the parking lights or low beams are on but goes off when high beams come on or are flashed?

- Looking at the top of the X50A underhood fuse block, it appears the fog lamps fuse (94) is pinned on my '17. Assuming there's connectivity from the (ghost) relay to the fuse pins, did anyone consider using a fuse tap to start the 12+ circuit to the lamps? I'm thinking if I can find the factory front fog lamp relay, adding a fuse tap to the F94UA fuse location might solve being able to use the BCM, once programmed by the dealer (who's willing to do that, BTW).
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Also, here's why LSs and LTs without Premium packages aren't capable of having fog lights... There is a separate bumper harness - part #23181386 - that feeds the collision sensors and cameras on the front bumper, and as it turns out, the fog lights. It's fed through the X100 connector up front on the passenger side. If you wanted to stay as close to factory as possible/practical, it wouldn't necessarily mean rewiring the entire engine compartment; it would require that harness (street price ~$70) and getting juice to it from the fuse block. Can't believe they put the fog light terminals/wiring on that harness when the front light harness could have carried them. Thanks, GM...

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Many thanks to all who've contributed here - Especially nilleo for the incredible detail and effort that went into his initial and subsequent posts.

Hello, I like your post. Is there anymore follow ups with the dealership terminated lead part #19301752. I know you posted awhile back. I'm trying to install to my 2018 Suburban LT. Thanks in advance.

 

[cmatt]

For those interested, I offer a fog lamp harness that gives you as close to factory functionality as possible without BCM programming.

Send me an email to [email protected]. There are three wires that need to be present inside the cabin. If they are not, I can supply the terminated leads to add them.

The current version will allow your fog lamps to stay on with the high beams. I'm working on a version that will turn them off when the high beams are on for those in states that prohibit them staying on.

Here's a video link where I go over the harness and its install.

 

[Michael Remer]

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.


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.


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:

Photo of after:


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!

 

[cmatt]

Thanks very much for the kind words Mike! I appreciate your input. Thanks to your idea, I’m working on another version (i.e. shorter wire lengths) to accommodate the alternate routing path. I’ll admit, my OCD can sometimes hinder seeing another option.

To expand on a couple things in Mike’s post, I designed the harness to mimic the factory wiring and routing as much as possible. The section that connects between the under hood fuse block and the bumper harness (section that secures to the bumper and connects to the fog lamps) was designed to run across the top of the radiator trim, connect with the bumper harness which travels down between the passenger headlight and grille. It does require the front grille and perhaps even the bumper to be loosened so the vertical portion of the bumper harness can travel up to the top of the grille and connect.

The routing path Mike took is certainly viable and negates loosening the grille/bumper. As mentioned he reversed the bumper harness section and connected to the fuse box harness section. This connection point exists in the event the front bumper needs to be removed.


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[cmatt]

Also, there are some verification steps I have folks take that helps me to know what’s needed for the install. One being the circuit that was missing in Mike’s vehicle. It provides the correct fused amperage to the X61A junction block where the latching relay connects for power.

It’s been my experience that fleet vehicles (and LS trim versions) are missing this circuit. I include the terminated wire to run at no charge.

It connects between the fuse block in the left side of the dash (X51L) and the back side of the X61A junction block just left of the brake pedal.

Here’s a short video showing how it routes.

And a pic of where it lands on the rear of the X61A junction block.



One other thing I’ve seen is on some early 2015 models. The circuit going from the cabin to engine bay that energizes the factory relay is missing. I also supply this terminated wire at no charge if needed.


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[Christian80]

It's definitely the same switch assembly in the body builder's schematic for both front and rear fog lamps at least for our US models ¯\_(ツ)_/¯.



For a low beams signal inside the truck--If you have halogens, yellow at the BCM, plug X4, pins 1 and 2 go out to the low beams (12V when on). If you have HID, it's still yellow at the BCM, but in connector X1, pins A2 and C2.

For switched ignition or accessory--there are tons of sources all over, I'd say check out the body builder's manual to see which one would be more convenient to you.

I used pin 1 on X4 connector for the switch on the fog lightsand I get a buzzing in the BCM in daytime but not on nighttime or if the headlights switch is on and not auto. My low beams act as DRL so they either don't get full 12 V or there is a issue with the fact that I installed LED bulbs and I no longer have halogen bulbs. Any thoughts?

 

[cmatt]

I used pin 1 on X4 connector for the switch on the fog lightsand I get a buzzing in the BCM in daytime but not on nighttime or if the headlights switch is on and not auto. My low beams act as DRL so they either don't get full 12 V or there is a issue with the fact that I installed LED bulbs and I no longer have halogen bulbs. Any thoughts?

It’s the Pulse Width Modulated (PWM) voltage the BCM sends to the low beam circuit. The most likely cause of the buzzing is the combination of the pulsed voltage and the LED bulbs.


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