I searched and read various threads here and elsewhere about hooking a light bar up so you can use the dimmer switch to turn the light bar on and off and I still don’t know if it can be done. One persons says use a relay, someone else says you can’t use the light module to control anything else, and others say they are going to do it but never post back the results.

I have a 2019 f350 super duty with the quad lights, NO upfitter switches, which I can work around, and I would like to add a 40-42” led light bar in the grill. I assume I would either have to use a three way switch, or two separate switches, so I can either have it always on or I can control it with the dimmer switch, off with low beam, on with high beam.

So my question is; can this be done, without damaging some module, and if so does anyone know how? I will state ahead of time I am not very knowledgeable regarding electrical stuff especially when it comes or resistors and diodes. Thanks Dan

 

I know this doesn’t help but why would you want it on when high beams aren’t on? I just relayed it off my high beams.

 

I run mine to a toggle switch on the dash in the 02. I would not wire them so that they come on with high beams unless it was a full-time off-road truck. In many places, light bars are illegal to run on public roads (many do it anyway) so having them come on every time you turn on the brights may be an issue. Out here in CA, we are suppose to run with our off-road lights covered. I see several trucks driving around that don’t have them covered and while I don’t see anyone getting pulled over specially for this, it could be used as an add-on if the officer decides to pursue it. Similar to our front plate laws. They generally won’t pull you over for it but they will either add the infraction or use it as a indicator for making an initial stop.

 

I don’t want it on all the time but when I do want it on I want to be able to use it only with the high beam. I didn’t notice, is your truck a 19 and if so how did you run the relay?

My truck is not strictly for off-road use and I understand the legal issues along with the debates as to why one would even want to be the rude person with the light bars blinding other drivers, which I’m not interested in. I drive in rural Montana with lots of critters on the road with very few other drivers, especially at night. What I am interested in is can I do this with a 2019 and if so how. Again, thanks.

 

On my 89 F350, I have a set of KC lights on my bumper that are relayed off of the high beam power, so any time the high beams come on, so do the KCs. I also have a switch in the dash to turn them off, if I wanted to for some reason. I don't think I've ever shut them off though.
On my 14 F150, it didn't come with fog lights, and in lieu of finding the correct switch and wiring it in etc, I relayed the fog lights off of the marker lights, so they are on with the low AND the high beams.
If I were you, I would just relay the light bar off of the high beams and call it a day. You could add a switch as well to turn it off, but I can't see why you would want to.

 

Finally found the post about the BCM. https://www.ford-trucks.com/forums/1...-question.html Second post by “Just Strokin”. This is why I’m asking specifically about the wiring in a 2019 so that I don’t fry something and incur more costs, which is typically what I do.

 

I did this on my last ‘19 with halogen lights and will be doing it again with the new one (also a ‘19). I tapped off of the high beam wire at the headlight, ran that wire into the cab to a switch, from the switch to a relay. The relay should receive the wire from the switch as the signal wire and the power should come fused directly from the battery. That way, with the switch on, the light bar will cycle on and off with the high beams. With the switch off, your regular high beams work as they should but the light bar will stay off. I put the switch in my glove box so, when I go for inspection, the lights are there but they won’t cycle with the high beams and they won’t be able to turn the light bar on.

with LEDs, it could be a much different animal but I had no issues with this setup on my truck with halogens.

 

I have mine on a 3-way switch. Up is on, middle is off, down is on/off with high beams. I have a signal wire coming off the high beam wire, with a diode, running to a relay.

 

i can’t think that LED’s would use more power than the halogen lights, from my understanding they are supposed to be more efficient. Will have to check that out. Thanks

saw a YouTube video, with basic demo running the same set up but no diode. How is the diode wired in and what type, or information, does one need to know about the “diode”. What purpose does the diode serve?

Thanks for the replies.

 

A diode is like a one way valve for electricity. You use them so you don’t unintentionally backfeed the circuit you just tapped into. It’s not necessary, in my opinion, but can’t hurt. You wire it in line with the wire you tap off the headlight circuit.

all I meant about the LED vs halogen is i’m not sure if the base truck wiring is more finicky with the LED headlight setup vs. halogen. In the scenario I wrote up, you’re only pulling an extremely tiny amount of power to trigger a relay. You should absolutely not use the leadlight circuit to actually power something else. That long light bar draws some decent amps. The individual LEDs don’t draw a lot but there’s a lot of them.

on a side note, wiring a long light bar like that to your high beams can make your high beams ineffective. Many of those longer bars are combo, flood on the outside and driving pattern in the middle. The flood pattern dumps a ton of light immediately in front of the vehicle, causing your eyes to focus there, rather than off in the distance like you want when you have your high beams on. That’s why your fog lights turn off when you put on your high beams. I ran a 32” combo bar for a bit but swapped them for Rigid hyperspot cubes. Very focused beam, long throw, very effective to compliment the high beams.

 

Good information sir and thanks. More to think about.

I assume there are different diodes for different applications so how does one know which diode to use?

I was considering the combo light bar due to the fact the there are a lot of deer, elk, moose and other critters that always seem to be down in the ditches, or right along the side of the road, so my thinking was if I could illuminate down the road and off to the side there would be less chance of one of them hitting me.

 

I tapped into the high beam wire (at the headlight), used it to trigger a relay, and powered my driving lights through the relay. The dimmer switch turns the driving lights on with the high beams. EZ peazy. On the 2018 Super Duty, the high beam wire going into the connector is a
20 ga, purple and orange wire (verify with a circuit tester).

 

I get why a combo bar looks good on paper but, in my opinion, they’re not ideal for high speed driving (highway speed). The flood portion of the combo bar puts a lot of light directly in front of the truck so, that’s where your eyes will focus. At speed, your reaction time and braking time means you need to be focused further down the road but your lighting selection is going to deceive you. You’ll have lots of light, but it’s not going where you want it. I’m running 4 hyperspots on mine and I can light up about 6 lanes wide a long ways out. Rigid also makes an RDS bar which is a curved bar but all hyperspot style LEDs so designed for throw but the radius bar gives you some width also (downside is they are pricey).

 

Thanks for all the info.

 

i have the LEDs on my 2020 platinum and it doesnt appear any wire to the headlight assembly has enough current for the relay

any leads would help