Yukon SLT Fog Lights Setting

WalleyeMikeIII said:

It seems doable...but I don't think you can do it automatically as the OP requested (so the fogs just come on whenever the headlights are called for being on). You could do it whenever you manually turn on the Headlights by also grounding out the fog lamp switch, I think). But, where the BCM just takes the input from the Ambient Light sensor and commands the Lighting Control Module to turn on the Headlights (via serial command, I think), there isn't an obvious way to do it that I can discern from the limited info at the Upfitter site.
From Pg 2-42
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In the Manual Case of flipping the headlight control switch to ON, I think one could short the headlight ON signal that is stated to be grounded to the fog lamp ON signal and achieve the fogs on w/ the headlamps, but this only works when flipping the headlight switch manually...I still see no way to imitate the automatic version above. At least not without some serious analysis of the Serial Messaging from the BCM to the LCM. But hey, I have been wrong before.
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Doubeleive said:

depends on the vehicle and lighting type, but "typically" drl's run on less than 12v, more like 10v probably, then when the ambient light sensor commands the lights on you will hear the relay click (in the engine bay fuse box) and then the full 12v's is applied. a separate relay could connected to that trigger to power on the fogs at the same time.
It's just a matter of looking at the wiring and connecting a to b, (power and ground + trigger)
depending on how it is done you could maybe end up with a error on the dic, the fog light switch may no longer turn them off if so desired, no fog light indicator lit up in the cluster etc, etc.
I would look and see if there is a specific fog light relay or if they are on a separate circuit. if they are on a relay then you should be able to just patch the headlight trigger to the fog light trigger and then test if the fog light button still turns them off
**then you have to consider the "on with wipers" also, if the trigger is set to work with the headlights then they should just come on with the headlights and go out with the headlights

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WalleyeMikeIII said:

There IS no relay for the fog lights...its a PCM from the LCM...Low current, because LED...

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Doubeleive said:

once voltage is confirmed it's as simple as running a power wire from the headlight circuit to the fog light, if the only goal is to have fogs with headlights
only thing i would check is if the ground or power is cut when high beams are turned on and then connect as needed

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Doubeleive said:

All generations of these trucks have a fog light button (if equipped) and all of them turn off the fogs when the high beams are activated and all of them engage the running lights if the fog lights are turned on alone and not the headlights and all of them turn off the fog lights when the key is cycled. It is a momentary ground switch like the tow/haul button.
that's it......
if anyone want's it different you have to DIY by means of wiring, relay, etc

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Bigburb3500 said:

I might have missed it but was BoostAuto discussed? Isn’t this exactly what you are looking for? It does not list the new Yukons or Tahoes but fits Silverados… might be worth trying at $23

1999 - 2024 GM Auto Fogs Mod

This kit allows your fog lights to automatically activate on your GM truck & SUV's from 1999-2024. Installation takes less than 10 minutes while following our video. Free shipping included, and MADE IN THE USA.

boostautoparts.com

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