Fog lights on w/ High Beams, New GM trucks

[Grit_dog]

Works just like on the last couple gen trucks.
New 2020 Silverado

Will see how much it helps.
Last Chebby, 2016 model, it was night and day difference (pun intended, lol).
Well not quite, but the OE fog/driving lights did a nice job of keeping the foreground lit when high beams were on.

Google it if interested. Hardest part is getting the diode wire into the back of the plug receptacle without kinking the wire. Small pair of needle nose pliers and making a "Z" in each diode lead helps.

They make "kits" which consist of 2 scotch locks, and a diode with some shrink tubing over it for $20. I like the cheap method, $1.99 for a 3 pack, A. because I'm cheap and B. No wiring modifications, no cut insulation. Completely removable and untraceable should there ever be an electrical issue (not caused by this).

Highly reccomended simple little mod.

And Karens, please don't bother with the "its against some rule" bs.

[BenK]

These are classic lighting beam patterns to give an idea of what they are designed to do.

But...on this thread, these functional beam patterns are not of interest...just cool factor...AKA looks

Nothing wrong with that...I was talking about function and the science...and the subconscious psychology of vision vs steering vs reaction time

Edit...example of the psychology of Vision & steering.

Freeway on ramp.

If you are trying to merge and see a vehicle driver looking/staring at you...careful, they will subconsciously match your speed to create a problem.

Meaning that when driving fast and you've lit up the near ground, you'll focus there
(where you haven't enough reaction time) instead of farther down the road where you do have enough reaction time

[Grit_dog]

JRscooby wrote:

rjstractor wrote:
I've never understood why foglights need to shut off when high beams are on, if someone is driving at you with their high beams on, foglights aren't going to make the glare any worse. With my VW and my Harley it's just a programming change.

LOL. In foggy conditions glare from oncoming headlights is generally not a issue. The water in the air will defuse most of that light. But what does happen is more of the light you shine out, the harder it is to see thru what is reflected.
Reading some posts I have come to the conclusion we need to look up the definition of fog lights, as different from driving lights.

Except rjs is spot on in his query and I have no idea how what you said is relevant to that.

[JRscooby]

rjstractor wrote:
I've never understood why foglights need to shut off when high beams are on, if someone is driving at you with their high beams on, foglights aren't going to make the glare any worse. With my VW and my Harley it's just a programming change.

LOL. In foggy conditions glare from oncoming headlights is generally not a issue. The water in the air will defuse most of that light. But what does happen is more of the light you shine out, the harder it is to see thru what is reflected.
Reading some posts I have come to the conclusion we need to look up the definition of fog lights, as different from driving lights.

[rjstractor]

I've never understood why foglights need to shut off when high beams are on, if someone is driving at you with their high beams on, foglights aren't going to make the glare any worse. With my VW and my Harley it's just a programming change.

[StirCrazy]

BenK wrote:
My point being that folks driving fast enough to need high beams and have fog's on at the same time might be distracted subconsciously by stuff lit up to close to do anything about at those speeds...and try to do something that might cause an accident

Thought PSA, but that got lost to most here...

I use it in deer or moose country, especialy on secondary roads. when i just have high beams on there ditch area is not light up as good as it is with low beams, but having the driving lights on this is fixed which gives you a chance to see the little buggers before they jump out of the trees right infront of you.

Steve

[ktmrfs]

01tundra wrote:

Grit dog wrote:
I question how full manual control of the fogs is possible with the Boostauto or DIY diode mod.
IIRC, Boostauto doesn't claim the ability to turn off the fogs when high beams are activated and it doesn't make sense that it would be possible. Last 2 trucks I did, the fogs were automaticlaly on with the high beams. Just like this one.
Regardless, if you have your brights on, it's for more light and the more the better!

I haven't really given it much thought, but I can confirm that the Boostauto kit does indeed allow you to turn the fogs on/off with high beams on via the factory fog light switch.

range of control of the fog lights on/off with high beam on may depend on the year of the truck.


On my 2015.5 GMC 2500HD denali the diode mod including the boost auto creates a logic OR function, not a logic AND function. Fog lights on if the fog light switch is on OR if the high beams are on. I have the full set of truck wiring schematics for the upfitters and the BCM control for the lights is done via logic states, not relays etc. and the boost auto (and as far as I could determine the ONLY way) to do the fog light control with high beam via logic functions basically "tricks" the BCM to think the fog light switch is on and the high beams are off.

Other years may have different logic for the BCM and may allow the fog light switch to turn the fog lights off with the high beams on with the diode mod installed.

[Grit_dog]

One might think, one topic that wouldn’t get resistance on a forum made up mostly of senior citizens ( generally eyesight and night vision degrades with age) is better vehicle lighting that DOESNT affect other drivers.
But I should have known better.....

[Grit_dog]

BenK wrote:
My point being that folks driving fast enough to need high beams and have fog's on at the same time might be distracted subconsciously by stuff lit up to close to do anything about at those speeds...and try to do something that might cause an accident

Thought PSA, but that got lost to most here...

Nope, not a PSA but thanks for playing.
Driving in the dark anywhere where there are critters that jump out at you randomly, having more light up close and a wider beam lighting the shoulders/ditches is not subconscious distraction, it’s self preservation of your vehicle.

[BenK]

My point being that folks driving fast enough to need high beams and have fog's on at the same time might be distracted subconsciously by stuff lit up to close to do anything about at those speeds...and try to do something that might cause an accident

Thought PSA, but that got lost to most here...

[01tundra]

Grit dog wrote:
I question how full manual control of the fogs is possible with the Boostauto or DIY diode mod.
IIRC, Boostauto doesn't claim the ability to turn off the fogs when high beams are activated and it doesn't make sense that it would be possible. Last 2 trucks I did, the fogs were automaticlaly on with the high beams. Just like this one.
Regardless, if you have your brights on, it's for more light and the more the better!

I haven't really given it much thought, but I can confirm that the Boostauto kit does indeed allow you to turn the fogs on/off with high beams on via the factory fog light switch.

[StirCrazy]

Grit dog wrote:
Works just like on the last couple gen trucks.
New 2020 Silverado

Will see how much it helps.
Last Chebby, 2016 model, it was night and day difference (pun intended, lol).
Well not quite, but the OE fog/driving lights did a nice job of keeping the foreground lit when high beams were on.

Google it if interested. Hardest part is getting the diode wire into the back of the plug receptacle without kinking the wire. Small pair of needle nose pliers and making a "Z" in each diode lead helps.

They make "kits" which consist of 2 scotch locks, and a diode with some shrink tubing over it for $20. I like the cheap method, $1.99 for a 3 pack, A. because I'm cheap and B. No wiring modifications, no cut insulation. Completely removable and untraceable should there ever be an electrical issue (not caused by this).

Highly reccomended simple little mod.

And Karens, please don't bother with the "its against some rule" bs.

if you would have bought the ford, you would just need to get free software conect to the computer and turn that option on. I have that, as well as changed how long my blinkers flash and several other features actavted.

weird you cant just do that for the GMC also.

Steve

[Slownsy]

Yes sir and in the land of OZ it is illegal to drive with fog lights on unless there is actually foggy conditions.
Frank.

[Grit_dog]

I question how full manual control of the fogs is possible with the Boostauto or DIY diode mod.
IIRC, Boostauto doesn't claim the ability to turn off the fogs when high beams are activated and it doesn't make sense that it would be possible. Last 2 trucks I did, the fogs were automaticlaly on with the high beams. Just like this one.
Regardless, if you have your brights on, it's for more light and the more the better!

[ktmrfs]

01tundra wrote:
I installed this kit on our 2017 GMC 2500HD, works great. It installs on one of the plugs inside the cab.

Allows you to use the fog lights on either low or high beam, fog light switch still functions as designed. So the fog lights only come on if you choose to hit the factory switch. All this kit does is prevents the fog lights from being automatically switched off when switching from low to high beam "if" you have the fog lights turned on.

After install your lights will function as follows:

Low Beams Only- Only Low Beams will be on
Fog Lights Only- Only Fog Lights will be on
Low Beams & Fogs- Only Low Beams & Fogs will be on
High Beams- Low Beams, Fog Lights, & High Beams will all be on (GM by default normally turns off the fogs when in high beam, but this kit solves that)

Running the fog lights with high beam in rural areas such as ours really helps....and before anyone wants to lecture me on how it's illegal because you could blind oncoming vehicles, I'm not of of the jacka$$e$ who approaches oncoming vehicles with my high beams on so it's a non-issue.

https://boostautoparts.com/products/6hi

one of my complaints about high beams on cars is that it usually reduces near field side visibility. It's a great mod and can either be done with the boost auto parts or using an appropriate diode.

Another good mod on earlier GM vehicles with quad headlights is to keep the low beams on with the high beams. Many cars do this, it is perfectly legal in all states. For some reason some quad headlight GM vehicles turn off the low beam with high beam on. My 04 silverado did that and I modified it so the low beams stayed on.

[Grit_dog]

On my trucks, the fogs always come on w high beams, as the diode jumper sends signal to fogs when high beam is lit regardless of whether fogs are on prior to or not. (Switches for lights are up stream of the jumper location)

Agree, though, it's a nice convenience to have a little more light when the high beams are on.
The no high w fog "rule" is one of those outdated regulations like 10k gvwr in 3/4 ton trucks.
Something about 4 beams total lit at once forward facing. Heck my truck has 6 beams on hi beam with no fogs lit.