Question: Adding a second switch for anytime fog lights

Has anyone wired up their fog lights on a 3rd gen to be run by the factory switch and also to be independently turned on by a secondary switch?

If it is easy enough to do I would like to set it up this way so I can run my fogs like normal and then have the option for them to be on with no headlights or on with my high beams via my Auxbeam switch panel.

Or if it is too complicated I will just unplug the factory wires and run the fogs solely from the Auxbeam panel.

My worry is about back feeding power and frying something in the switches or causing an electrical fire. I have wired a lot of accessories in vehicles over the years but it was always just one switch through a relay or tapping into factory power, never doing both at the same time.

 

You can use 2 diodes, or use a relay to make it do what you want.

If relay:

86 - power from added switch
85 - ground
30 - connected to wiring going to fogs
87A - goes to power side of existing fogs
87 - battery power that will go to the fogs when you have the added switch clicked.


If you go the diode method:

Just splice your switch power into the fog circuit and put a diode on your power wiring to the fogs and also on the wiring coming from the truck. So essentially all power wiring has a diode and then the wires merge after the diodes and go to the lights.

 

Thanks

So for a relay it would just be powered by either the oem switch or auxbeam switch.
Seams simple enough. I was thinking I'd have to run diodes in each line

 

The relay wired like mentioned above will keep the circuits separate to prevent needing diodes. It’s a bit more work to do it that way vs diodes and merging the wires, but I think it’s a better solution.

 

While looking around for ideas I stumbled across Roadmaster Hy-Power diodes, they are incased in epoxy so I should be able to mount it in the engine bay and splice right at the OEM fog light wiring.

I might pull apart the loom in front of the battery and put the diode on the green wire there.

Would I need to tie the auxbeam switch into the ground wire at the same location or just ground it to the frame since the fogs have a ground going through the oem relay?


https://www.roadmasterinc.com/hy-power-diodes/