I installed a LED bar around Christmas time, its been on and working great for some time. Today i smelled some weird electrical smell while driving and figured that couldnt be good. I did some investigating in my console and found this tonight.



This is the wire that melted the loom in the pic above. Looks like maybe a diode or whatever got too hot or shorted out.



Now, i know first thing everyone will think is how did you wire your light. I used the drawings i found below;



and this one



What exactly would have caused this? Could the diode just go out on me? The switch wont work obviously so im hoping i didnt blow the OEM AUX switch. I know the OEM wiring in the harness is very very tiny, could it just have maxed out the little wiring?

Can i just rewire it with bigger wiring without a diode or whatever is in that wire which melted?

Anyone have any idea?

Which wire was it that melted? I don't see any diodes in that diagram?

First off - glad you caught it and it wasn't any worse.

Did you follow the wiring diagrams to the letter? Just wondering what the purpose of the diode is and if that's the part that burned. Which actual wire melted? Was it the signal wire?

The diode is in the oem wiring. I did a ton of googling last night and its apparently there for oem wiring. As if I was plugging in to factory system. It's so the computer won't overload the switch. But a lot of people instruct to remove the wire with the little diode in it and wire a normal wire and have no issues. Its been hooked up for a month no issue then I was driving with it off and smelled plastic.

Its the red/green wire so its the wire in which leads to the relay.

Do you know what load the diode was rated to handle?

Couldn't find that info. I have a 5amp fuse from the relay to the switch and its not blown.

I would imagine the diode is between 1-3.5A and it is certainly possible that it melted because the draw was too much.

How long was the bar running before the melting occurred?

the bar draws 180w/12v = 15amps through a relay. The relay coil typically pulls <1 amp.

bar wasnt on. Thats why im confused. I've left it on for an hour with me watching everything previously and nothing.

I've noticed that sometimes the plastic cover over the shifter gets pretty hot sometimes, are you sure that it wasn't touching anything that got really hot?

You have the relay between the switch and relay or between the power and the switch? There should be one between the switch and wherever its power is from.

All the FJ switches I've installed I've cut the harness past that diode (didn't actually know it was a diode) before installing. Not sure if that's right or wrong but they've worked fine for 4 years.

Didn't you previously cross the wires or something? COuld it have been from that?

could very well have touched it. I havent fully opened up the wiring as it was dark. Planned to do it here soon, but the switch is inoperable now.

theres a relay which is fused from battery to relay and fused after the relay to the switch. Also fused from green trigger wire to power.

I'm still trying to understand what part of the harness wiring has a diode in it? Is it to do with the OEM fog light switch (did it come with it's own harness?)

ie. of the diagrams you posted - which wire melted?

It's in the switch's harness, and I think the green wire.