Utilizing the factory fog light button with aftermarket lights

[Kyle McWilliams]

This may be one of those things that is just far too difficult to be worth while, but i am hoping you good people can give me a hand.

I've got a 2014 Ram 1500 Sport, and after ripping the front bumper off 3 or 4 times in deep snow and mud - I went with an aftermarket steel bumper with far more clearance.

I'll be installing ~120w of LED light that I would like to be activated by the factory fog light button and light up the fog light symbol on the gauge cluster. To make it a bit more difficult, I am hoping to be able to use the fog lights with the DRLs or high beams too (factory setting only allows the fogs to be on with the low beam headlights).

Thanks!

 

[Brandon-w]

Alfa obd. Is your best bet. You can hook up LEDs to your existing stock harness and change the settings to activate led capability without canbus or resistors. You can also set what location you want your drl and can set it to keep fog lights on with high beams. I like this because there's no extra wiring and no hacking at the stock wiring to make things work. Hope this helps.

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[sbarron]

I did exactly this by having the OEM switch trigger a relay. I have Rigid Hi/Lo driving lights in the fog openings (the standard dual cube setup) where the low beam is run from the OEM fog light circuit and the high beam is triggered by the OEM hi-beam circuit. The second set are Rigid hyper spots triggered by switch and high beam circuit.

 

[sbarron]

Alfa obd. Is your best bet. You can hook up LEDs to your existing stock harness and change the settings to activate led capability without canbus or resistors. You can also set what location you want your drl and can set it to keep fog lights on with high beams. I like this because there's no extra wiring and no hacking at the stock wiring to make things work. Hope this helps.

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Not sure what the OEM fog light switch/wiring is rated at, but 120W is ~10A. Still may require a relay for isolation.

 

[John Jensen]

What Brandon-w said is what I did.

 

[Brandon-w]

Not sure what the OEM fog light switch/wiring is rated at, but 120W is ~10A. Still may require a relay for isolation.

I think the 120w is the output of the led output not the consumption. From experience the stock harness will take 130 watts of actual halogen draw (had 65w lights in fogs before I upgraded) and never had a problem

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[sbarron]

I think the 120w is the output of the led output not the consumption. From experience the stock harness will take 130 watts of actual halogen draw (had 65w lights in fogs before I upgraded) and never had a problem

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Yes, 120W is the output, but it takes 10A of input for the lights to generate 120W of output @ 12V.

 

[mtnrider]

Not sure what the OEM fog light switch/wiring is rated at, but 120W is ~10A. Still may require a relay for isolation.

The headlight/fog light control is run through a circuit board in the TIPM that is on a 20a service(total). I'm sure the wiring will be good for 30a but the danger is frying that circuit board in the TIPM, that can get expensive. Best bet is to run a separate relay (for several reasons).

.

 

[Kyle McWilliams]

"120W" on an aliexpress lightbar i expect to be fairly lower actual draw and output. I dont want to risk frying any boards but i think that draw is within the same ballpark as the oem fogs?

 

[Jimmy07]

I think the 120w is the output of the led output not the consumption. From experience the stock harness will take 130 watts of actual halogen draw (had 65w lights in fogs before I upgraded) and never had a problem

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Yes, 120W is the output, but it takes 10A of input for the lights to generate 120W of output @ 12V.

Watts has nothing to do with light output. That’s measured in lumens and the two don’t correlate or convert. It would be like trying to convert inches to gallons. Wattage is simply how much energy is used to power the bulb.

 

[Jimmy07]

"120W" on an aliexpress lightbar i expect to be fairly lower actual draw and output. I dont want to risk frying any boards but i think that draw is within the same ballpark as the oem fogs?

A 120w lightbar draws 120w. Oem fogs (9006 for the 1500s) are 55w.

 

[Brandon-w]

A 120w lightbar draws 120w. Oem fogs (9006 for the 1500s) are 55w.

Ok I think we get the idea now. Mtn rider and some others have clarified this clearly in above comments let's not beat a dead horse here. Throw in a relay and be done no worries then end of story. [emoji106]

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[Jimmy07]

Ok I think we get the idea now. Mtn rider and some others have clarified this clearly in above comments let's not beat a dead horse here. Throw in a relay and be done no worries then end of story. [emoji106]

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That would be the best bet. 10 amps is a lot of current being passed through the 20awg fog lamp driver wires over that length (from the lamps to the gas pedal where the bcm is located).

 

[Kyle McWilliams]

I'm getting a spam filter when i try to post the link, but if you pop "2014 ram 1500 fog light draw" into google there is a spec sheet pdf that comes up on the top.

It lists fog lamps as 12.1A maximum allowable continuous draw. Two 55w bulbs puts the stock system at 110w or ~9.2A.

 

[sbarron]

Watts has nothing to do with light output. That’s measured in lumens and the two don’t correlate or convert. It would be like trying to convert inches to gallons. Wattage is simply how much energy is used to power the bulb.

Even more accurate, except that lumens, (especially as claimed by lightbar mgs) is all smoke and mirror.

 

[Kyle McWilliams]

Ill just document for someone using search later, but i crawled under the truck and it looks like they wire the factory fog light harness with 2 grounds and 2 hot wires (all appear to be the really small 20awg as mentioned above) going back to the TIPM or wherever they go.

I should mention that i am powering 2 separate lightbars, each will be 60w draw (not a single 120w). So if i wire each bar to its own factory hot and ground in the existing harness, that will be 5w more load per circuit over the factory incandescents.

To make it even more complicated, the lightbars are actually 150w each. They have 60w of flood light and 90w of spot light per bar. It is the two 60w portions that i want to run off of the factory controls, and I will run an entirely different relay/switch for the two 90w spot lights.

Tldr; Going to wire up two separate 60w LED flood lights to the factory fog light harness (which powers two separate 55w bulbs normally).

Thanks for all the help, I'll update you guys when i melt my dashboard.

 

[John Jensen]

I am running 4 Baja Designs wide angle quad LEDs (2 quads per side) that are rated at 26W/2A per each quad. I connected to the factory fog harness so I could use the factory fog switch. Been on for a year, sometimes as DLRs, sometimes as fogs - never a hint of a problem.

I'm not sure we can use basic electrical rules on our Ram's as the Canbus system is a strange and misunderstood system. I'm told it is an electrical pulsating process which allows for high loads over small gauge wiring. All that said, I have no idea if any of what I said is correct.

Hope this helps you decide.

 

[Kyle McWilliams]

I am running 4 Baja Designs wide angle quad LEDs (2 quads per side) that are rated at 26W/2A per each quad. I connected to the factory fog harness so I could use the factory fog switch. Been on for a year, sometimes as DLRs, sometimes as fogs - never a hint of a problem.

I'm not sure we can use basic electrical rules on our Ram's as the Canbus system is a strange and misunderstood system. I'm told it is an electrical pulsating process which allows for high loads over small gauge wiring. All that said, I have no idea if any of what I said is correct.

Hope this helps you decide.

I appreciate the input John, I'm going wire those 60w floods to the factory harness. I'm fairly confident that the factory wiring can handle that load. I'll see about getting AlfaOBD as well, to program fogs to run with high beam. Alfa looks fantastic, as i can correct my wheel size when i eventually step up to 35s.

 

[sbarron]

I am running 4 Baja Designs wide angle quad LEDs (2 quads per side) that are rated at 26W/2A per each quad. I connected to the factory fog harness so I could use the factory fog switch. Been on for a year, sometimes as DLRs, sometimes as fogs - never a hint of a problem.

I'm not sure we can use basic electrical rules on our Ram's as the Canbus system is a strange and misunderstood system. I'm told it is an electrical pulsating process which allows for high loads over small gauge wiring. All that said, I have no idea if any of what I said is correct.

Hope this helps you decide.

The RAM canbus system is easy to understand in its correct context. It's in the same box as witchcraft and magic. Or women.