Need help wiring factory fog light switch

[crankyjew]

howdy yall-

I picked up an 01-03 radio bezel with the fog switch to use with my led light bar.

I previously had just toggle switch hooked up, with a relay. I'm drawing power from my high beam circuit with a fuse tap to energize the relay. worked fine, but not very clean and I didn't like the bright blue led. like this

I found these instructions for using the factory switch.

help me wrap my head around this-
Do I 1) need to run a high-amperage line back into the cab to pin 6 to run the indicator light? 2) need to run my supply line from the interior fuse panel back out to the relay?

 

[01STrunner]

Here's another thread with more links that may help (theres a diagram in the 1st post as well): https://www.explorerforum.com/forums/showthread.php?t=203037

1) I dont think you need the high amp line to the switch. Pretty sure that can be any 12V source. If you look at the diagram in the link I posted, he has the 12V source as the parking lights which in his case is only a signal wire. In one of my switches, I actually tapped into the 12V outlet in the console to supply the switch with power. The other is direct from the fuse box.

2) I think you do need to run the power from the fuse box to the relay since it's the relay that provides the power to the lights.

 

[crankyjew]

thanks for the reply. but that link detailed pretty much my previous setup, with a normal toggle switch. the factory fog light switch has some funny things going on that are confusing me. maybe I wasn't clear in my first post..

 

[Flounder]

As to 1), why not tap pin 6's wire to pin 3's wire? When the switch is engaged, pin 3's wire should be 12V hot, which, in turn, will illuminate the light.

As an aside, I did the same project you are doing, but ran a wire from pin 3, through the firewall, and to the 12V hot wire after the relay. In hindsight, it seems like a useless endeavor given the above.

 

[Kjhadfield]

Did you check the radio bezel stickie above? That has some useful info- has some wiring explained that may help you

 

[crankyjew]

I did indeed. it didn't really answer my questions without creating more. the problem with old posts about wiring is things like "splice into the white wire." well, I didn't buy any white wire for my setup. I understand this is fairly simple- but in the moment it's an extra factor I don't need.

I found and old post on another forum that said simple $5 toggle switch setups function by breaking the hot side of the relay, whereas the factory switch works by breaking the ground side. this helps a lot.
[MENTION=1022]Flounder[/MENTION], good idea. It seems nobody else has done that, I wonder why?

 

[Alwayssideways]

when I wired mine in. I pulled the power to the internal light inside the switch from the same wire the stock fog light had. I then ran a 12v source from the 12v aux to the lights and come to find out (after several attempts) the stock switches cut the ground and not the 12v. It took me a try or 2 to figure that out.

 

[Flounder]

the stock switches cut the ground and not the 12v.

Makes sense. So, my suggestion of tapping the two won't work.

 

[koda2000]

Cranky, sorry if already know all this but...

Relays work by always being connected to a 12v source (usually w/key ON) and are usually energized by a low amp switched wire delivering 12v on a thin gauge wire. Once energized the relay delivers 12v over heavier gauge wire to the lights. The relay should be placed as close to lights as possible to reduce resistance in the wiring.

As the relay also has a ground wire maybe you could break the ground using the bezel mounted switch and always run 12v w/key ON to energize the relay once the ground is restored by the switch. Does that make sense?

 

[crankyjew]

yep, thanks for the feedback. I'm pretty well aware how relays work, but again thanks for the head up!

so- right now I'm breaking the 12v to the relay with the ford bezel switch. it wasn't made for that and while it technically functions, my light bar works, the switch doesn't light up at all. you're totally right- I need to run 12v to the relay directly, and break the ground with the switch. seems backwards to me, but a combination of you guys and my ford manual, I've got my head wrapped around it.

As far as running switched-on 12v to the relay, I'm going to stick with my fuse-tap off of the high beam circuit. It means having to run another wire through the firewall, but I like the functionality and flexibility. I can change when my light bar will work just by changing were the fuse tap plugs in. That saved me from a fixit ticket on a previous vehicle.

I'm still chasing some unrelated wiring gremlins elsewhere on my ST, but once I get around to redoing this project I'll report back!

 

[koda2000]

yep, thanks for the feedback. I'm pretty well aware how relays work, but again thanks for the head up!

so- right now I'm breaking the 12v to the relay with the ford bezel switch. it wasn't made for that and while it technically functions, my light bar works, the switch doesn't light up at all. you're totally right- I need to run 12v to the relay directly, and break the ground with the switch. seems backwards to me, but a combination of you guys and my ford manual, I've got my head wrapped around it.

As far as running switched-on 12v to the relay, I'm going to stick with my fuse-tap off of the high beam circuit. It means having to run another wire through the firewall, but I like the functionality and flexibility. I can change when my light bar will work just by changing were the fuse tap plugs in. That saved me from a fixit ticket on a previous vehicle.

I'm still chasing some unrelated wiring gremlins elsewhere on my ST, but once I get around to redoing this project I'll report back!

Ok, sound good. I find there are a lot on instances where auto manufactures break/restore the ground connection to turn stuff on/off. It seems to be mostly relay related. I think maybe there's less amperage across the switch contacts by doing this, but that's just a guess.