Easy 5 min anytime fog light relay mod DIY

yes.

https://www.tundras.com/threads/diy-fog-light-mod.371/

 

Thanks but that’s very foreign to my electrical abilities.

 

Trust me when I say I know exactly what you mean. I prefer the plug n play option but sadly there isn't one. So I opted for the anytime foglight option using the stalk for now. But I plan to do the anytime switch in a month or two. Just the thought of cutting wires leaves a bad taste in my mouth. I love plug n play.

That's how I did all my fog light wiring for my motorcycle. All plug & play. No splicing, cutting, tapping into original wires.

 

Lol I’m thinking of go same route as you with the stalk. And yes, a plug n play would be awesome.

 

Did anyone figure out how to do this with a 19 yet?

 

Did this on a 2021, with slight modification. No idea on differences between years but I did it differently to make it work with my 2021.

Stock 2021 fog lights are controllable with factory switch with parking lights and low beam. Only times fog lights don't work are with high beams and daytime running lights. All I wanted was to also have fog lights with high beams.

2021 fog, low, and high beam relays are all switched on the coil ground. So as others have commented on newer years, grounding the coil ground turns the fog lights on at ALL times, can't be turned off. There has also been mention of connecting the fog coil ground to the headlight coil ground. For a 2021, connecting to the low beam relay for example, causes the fogs to turn on every time the headlights are on, and causes the low beam to be on every time the fogs are on. While this turns the fogs on with brights, it also turns the headlights on with park lights. Same concept if fogs are connected to the bright relay.

To maintain parking lights I added another relay that is triggered by the high beam relay. What this does is turn the fogs on with high beams but doesn't turn the high beams on with the fogs. The only thing that changed from stock is that I now have fogs with high beams. All other functionality is exactly the same. I can't turn the fogs off with high beams, fogs are always on with highs, but I'm ok with that.



Also should be noted that I did NOT bend any relay tabs over. If someone tries to duplicate this and bends tabs over, it's not going to work.

 

Can you post up additional pics where u jump those wires on the additional relay prongs so i can duplicate it? please i needed fogs with high beams.

 

What is it you're looking for? What's your understanding of electrical, relays, etc?

 

Will this technique work for the high beams also? I just installed a Rough Country hood bulge amber/white LED light strip and want to make the amber come on when the fog lights are turned on abs the white turn on when the high beams go on. Trying to stay away from a rocker switch and keep it stock switches. Any thoughts?

 

I did the first mod listed years ago on my 2010. No DRL's or Auto Headlights. I really don't see the need (for me) to have fogs on in daylight. We have a law here in MD that tells us to have headlights on in the rain, nothing more than common sense. My headlights are on in any inclement weather anyway but fogs only after dark. My Ridgid Fogs with Amber covers take care of the thick stuff!And fogs can stay on with high beams if needed.

 

Hi Nick, you might have me confused with another member, I have no pics of what I've done. I'm also not sure if my mod would apply to your 2021. If you search on here for 'Eddie's fog light mod', the old method I used will come up. Good luck!

 

Unfortunately our 18+ are wired different and I'll have to used this mod instead of rewiring. I wish I could figure out how to rewire so I can just have fogs on if I want. With the relay grounding out method, my fog switch becomes obsolete. Any electricians done the rewire for an 18+?

 

So basically use a different oem location for a different switch? I don't have any open oem locations. I'd like to use the factory fog switch. I guess I'll try to figure it out with relays and DMM.

 

You are not going to be able to use the factory fog switch. It’s hard wired to shut off when the high beams are on, the only way to bypass that is to bypass the switch

 

So confused about the wiring options on a 19. Could someone explain the options for having fogs with high beams on a 19. Thanks!

 

Did you ever get follow up with this? sounds like what I need for a 2019 CM.

 

1. Pull out the fog relay (in the engine bay behind battery there is a box that contains most of the relays)
2. Bend the negative arm to 90 degrees and attach connector to it
3. From the connector should be a short (3inch) piece of wire
4. Take out the high/low headlight relay (it’s a much bigger one)
5. stuff the end of the wire under the negative prong of the headlight relay, put the relay back in

now you’re done. the fog light is grounded when the low/high beam is grounded (always)

 

This is the solution @captainyomo

 

thanks! is there an easy way to identify the negative terminal of the headlight relay?

 

I have a 2018 tundra sr it didn’t come with a fog switch on the headlight stalk but has the wiring harness for them. If I add the fog relay and do the trick of bending the tab on the relay and grounding it will they come on with my lights lo/hi/running lights? Or do I need to install the headlight stalk with the fog switch?

 

I’m interested with the harness too. I have an aftermarket fog lights for my 2011 and I can’t make it work with the original harness that is available.

 

After reading this thread I think we need a full tutorial on how the entire fog light system works. I have been considering doing this anyway. Maybe will make a YouTube video.

There is definitely a way to do this and still utilize the factory fog light switch. It would essentially be a combination of both versions of the mod.

With the key ON the factory fog light switch would turn on/off the fogs no matter what conditions of headlights ect. You wouldn’t have the situation here where they just come on with the headlights.

The entire circuit would be dependent on key on (battery power) and the factory fog light switch (on/off) that is it

 

It will also depend on year.
With 2018 they overhauled be fog light system and it does not function the same

 

I agree. It would be greatly appreciated.

 

I was going to pull up the 2018 EWD this morning to look at what they changed.

The 2022 guys I think the entire light system is driven by CAN bus signals which makes it even more difficult.

 

This is not correct. The factory fog light switch is just an On/Off switch, however the signal from it is routed through the body control module. The BCM shuts it down when the bright lights come on.

The original Eddies mod uses the factory switch but bypasses the BCM not longer allowing it to kill the circuit with the brights come on. You can still use the factory switch.

The mod shown on page one of this thread does the same thing except it bypasses the BCM AND the factory switch cutting both out of the circuit.

 

This is one of the things that the 2018+ changes impact
Pre 2018, the headlight relay powered the fog lights too (with the ECU/BCM providing the additional control over when they were on). This is why the fogs would not be on with only parking lights active. 2018+ power to the fogs is provided directly from battery, so now they can be on with just parking lights but now if you do the Fast Eddy V1 mod, you end up with your fog lights on any time the switch is on (even with the truck off)

*going off of memory here. There may be some slight inaccuracies in how I am describing things

 

Yes this is what the wiring diagram shows.

If I was to do it, I would bend up the positive coil tab on the relay. Slide on a spade connector with and add a fuse and go to the ignition fuse. Doing so would control power to the positive side of the coil with they key on/off.

Then go under the dash to do the Eddie’s mod to remove the BCM, making the factory switch the only control over supplying ground to the negative side of the coil.

Doing it this way would mean anytime the fog light switch is on, the coil has a ground signal. Anytime the key is turned on the coil would have a positive signal. Fogs would come on/off with key and you could control them with the factory switch at anytime during operation.

It’s a combination in a way of both mods but gives you total control. About the same amount of work as well.

Im not that big on add a fuse so if I was to really do this I would pull the fuse box apart and more permanently join the power side of the coil to an ignition controlled power source in the fuse box.

 

Your theory makes perfect sense to me. Has anyone done this to a 2018?

 

I don’t think anyone has done it at all yet. You can be the first!

I have the 2018 wiring diagram and can show you how.