Fire averted!

[BigMex]

I looked at the product and you do not need that relay or that switch to make it operate, it seems like your inexperience at wiring help cause this.
The aux switch can directly power these LEDs, my front foglights from Oracle are wired directly to the aux switch (#6 10 amps they only draw 6), they tell you to cut the relay and the switch off whe using Aux connection
I can't imagine that those LEDs take more than 10 amps, that is switched 3 through 6.if it is 15 use 2.


Here is few tips.
Don't use vampire clips on anything
Don't have big bundles of wire cut it to length.

When I add accessories I use heat solder connectors that are waterproof.

Thanks! I appreciate the practical advice. My electrical skills are definitely novice-level.

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[BigMex]

UPDATE:
In this first picture, these are the wires downstream of the relay used to connect the two LEDs to the battery and the switch runs. This is the switch run (split in half - connected at the two white plugs). These are the wires that turned RED HOT and melted. I cut it short of the relay.

in this picture, you can see the relay that brought everything together, and the run to the battery with the inline fuse. None of these wires achieved ignition temperature, and were normal to the touch while the switch run got hot.

here’s a close up of the relay inputs (I carefully pulled away the black sheathing & insulation) with a view to the melted switch run wiring.

I appreciate any expert diagnoses you may be able to offer. Thanks!

 

[Navyicman]

Here is few tips.
Don't use vampire clips on anything
Don't have big bundles of wire cut it to length.

When I add accessories I use heat solder connectors that are waterproof.

Just another 2 cents, i like to use weathertight connectors. They are fairly in-expensive on amazon and with the proper crimp tool, also on amazon fairly cheap, they go together really easy.


Here is a complete kit

https://www.amazon.com/dp/B09ZXDSC6G/ref=syn_sd_onsite_desktop_0?ie=UTF8&psc=1&pd_rd_plhdr=t

 

[Navyicman]

UPDATE:
In this first picture, these are the wires downstream of the relay used to connect the two LEDs to the battery and the switch runs. This is the switch run (split in half - connected at the two white plugs). These are the wires that turned RED HOT and melted. I cut it short of the relay.

in this picture, you can see the relay that brought everything together, and the run to the battery with the inline fuse. None of these wires achieved ignition temperature, and were normal to the touch while the switch run got hot.

here’s a close up of the relay inputs (I carefully pulled away the black sheathing & insulation) with a view to the melted switch run wiring.

I appreciate any expert diagnoses you may be able to offer. Thanks!

Okay, without being there to totally dissect the burnt harness. it looks like the short occurred on the yellow lead in the aftermarket switch harness, maybe even in the coil of the relay. The rating 12V 40A printed on it refers to its switching capacity, not the rating of the coil.

From the looks of it, it was designed to have switch energize the coil of the relay. Was there a switch on the aftermarket harness that you removed to do the wiring? This indicates to me that the relay is energized by the switch and it closes contacts that power the lights; which is not needed with the Ford factory Aux switches, they have their own already installed.

It also looks like you were using Aux #1? If so that is a 25 amp circuit, After re-reading your OP,I see you are using Aux#6, 5A but still plenty of power to cook wires/relay coil if they are undersized/not rated for it or even mis-wired due to a mis-understanding of the Ford upfitter wiring. When you pulled the fuse, there still was power to the relay from the Aux switch leads, thus it continued to cook. One thing to know about splices is if they are poorly executed, the resistance is higher, causing heat to build up and damage things, thus possibly leading to a short.

I saw the aftermath of a poorly executed splice on a 355 VDC system that was using 4 aught cable (really big stuff), the bad splice eventually shorted to ground and a fire broke out that destroyed the entire cable bank. estimated damage ~1.5 million dollars.

 

[BigMex]

Okay, without being there to totally dissect the burnt harness. it looks like the short occurred on the yellow lead in the aftermarket switch harness, maybe even in the coil of the relay. The rating 12V 40A printed on it refers to its switching capacity, not the rating of the coil.

From the looks of it, it was designed to have switch energize the coil of the relay. Was there a switch on the aftermarket harness that you removed to do the wiring? This indicates to me that the relay is energized by the switch and it closes contacts that power the lights; which is not needed with the Ford factory Aux switches, they have their own already installed.

It also looks like you were using Aux #1? If so that is a 25 amp circuit, After re-reading your OP,I see you are using Aux#6, 5A but still plenty of power to cook wires/relay coil if they are undersized/not rated for it or even mis-wired due to a mis-understanding of the Ford upfitter wiring. When you pulled the fuse, there still was power to the relay from the Aux switch leads, thus it continued to cook. One thing to know about splices is if they are poorly executed, the resistance is higher, causing heat to build up and damage things, thus possibly leading to a short.

I saw the aftermath of a poorly executed splice on a 355 VDC system that was using 4 aught cable (really big stuff), the bad splice eventually shorted to ground and a fire broke out that destroyed the entire cable bank. estimated damage ~1.5 million dollars.

Any advice on how to proceed?

I have two red & black pair of wires each leading back to the lights below my rear bumper, and no way to get juice to them and switch it all up with Aux #6. Thanks in advance!

 

[4x4TruckLEDs.com]

Unfortunately it seems like most of these vendors use cheap china-made harnesses. I had great experiences with 4x4TruckLEDs (sarcasm) when fog light pigtails were pins incorrectly - I inquired and was very rudely told that "their harness aren't wrong"...until I sent a picture. I also noticed that, at least on their 3 light (pocket fog lights) harness the common return wire is the same gauge as all of the other wires - so if each pair of lights is running at close to the max rating for 16AWG, that means that it is exceeded by 200% if someone turns on all 3 lights... I was told that they "haven't had a problem yet". Hopefully nobody really leaves all lights on at once, or they are as good as you at catching it...

Our wire harnesses are oversized for this purpose... rather then have a larger ground and then smaller power wires, we opted to make all the wires the same gauge so that they all matched the ground wire.

At most you'd be pulling 18 amps if you had 6x Diode Dynamics SS3 Max.

 

[Navyicman]

Any advice on how to proceed?

I have two red & black pair of wires each leading back to the lights below my rear bumper, and no way to get juice to them and switch it all up with Aux #6. Thanks in advance!

I would have to look at it to give a best recommendation, but there is one unpowered aux wire that goes to the rear down the passenger side (E) . I would take power from A6 to unpowered wire B1 or B2, connect that to wire E, and then get power from E to your lights by fishing through the wheel well area. There are a bunch of posts on here about the aux switch wires and how to utilize them.

 

[Offroad Newb]

Any concern that the way you had the excess harness bundled caused additional heat build up?

I have the pillar lights and fog pocket kits bunched similarly near the upfitter switch wires and want to make sure there wouldn’t be too much heat build up with it coiled too close.

 

[BigMex]

Any concern that the way you had the excess harness bundled caused additional heat build up?

I have the pillar lights and fog pocket kits bunched similarly near the upfitter switch wires and want to make sure there wouldn’t be too much heat build up with it coiled too close.

I am certain my bundling didn’t help, although I doubt it was the cause. I think I created a short circuit.

 

[sn95]

Thank you for posting this information. I'm glad your Bronco was not damaged how it could have been. Did F150LEDS respond to your findings? I'm curious to what they had to say if anything. Thanks

 

[SPVPARTS]

Thank you for posting this information. I'm glad your Bronco was not damaged how it could have been. Did F150LEDS respond to your findings? I'm curious to what they had to say if anything. Thanks

This an interesting post. We must have missed it earlier.

So funny enough, this post hits it right on the head. All wiring isn't created equal.

In fact, almost all the "supplied" wiring you get with various lights is adequate at best. Especially the "cheapy" Ebay/Amazon lights.

It all comes down to a few things. There is a minimum standard to what is considered "automotive wiring". That standard is that the insulation heat resistant to 105 deg Celsius. (Thats about 200 deg Fahrenheit)

That doesn't account for a few things though. One is heat from an engine compartment or component.
The other is power draw creating heat. Such as the resistance created from nearing or exceeding the amp draw on certain wire thickness (gauge).
Also how good the crimps, connections or connectors are. If there is a loose connection, it causes excess load and then creates heat.

When you take all those things and combine them. That 200F can easily be reached. Well before a fuse is blown.

Often times these cheap harnesses have fuses that are higher capacity than the wire rating. Which mean your first line of defense, the fuse, never blows before the wire melts.

So yes. Wiring is a VERY important factor. Many and I mean almost all the "generic" harnesses that come with lights (especially the cheap brands) are cheap cookie cutter budget Chinese $5 or less cost to produce in bulk.

It's not "China" that is the issue. It's the companies that want the cheapest thing they can buy so they can say they supplied you with something. Iphones are made in China too. But they are quality controlled and to APPLES specification. Not Allibabba.com

I am of the mindset that I don't want to "Overspend" but I want to look for "inexpensive" not "Cheap" You don't want to sacrifice quality.

So for those of you who are unfamiliar. We patented and produced the first plug n play modular harness system. We however produce our harnesses with industrial grade wiring. Not just to "general purpose automotive wire standards".
So we use industrial grade wiring with a high heat (200 deg Celsius, which is 392 deg Fahrenheit)
Our harnesses are made to meet and EXCEED the wiring in Ford vehicles for heat and corrosion resistance.
We also only use high quality loom and wrap. This is another area place skimp on.

So the point is. Metal is metal. Copper is copper, etc. You may have some heat from various environmental factors. If that happens, the insulation our harnesses will not melt like the budget stuff out there.

I have seen issues like this a lot. So we actually did a little science experiment video to demonstrate. If you haven't seen it. Here it is.

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