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LED wiring help

I

Ian Christiansen

NAXJA Forum User
Location
Shelby Township, MI
I'm installing a 100 watt led light bar I purchased from Olympus. They were helpful with the wiring diagram but I need help finding a 12v source for the on/off switch that turns on with ignition. Can I splice it into the positive wire for 12v auxiliary plug? I have two and one only works when the ignition is on. It's a 2001 XJ.
 
Wired correctly it won't.... (and you don't leave it on...)

The control side of relays pull very little amperage.. I would just tap into the hot always 12 volt outlet, no need to run another wire to the battery for the CONTROL SIDE.

And just cause, I prefer to ground switch relays. So I jump the wire coming from the battery to 87 or 85 on the relay, then I just ground the other side 87 or 85 with the switch in the cab. No need to find a hot wire in the cab that way.
 
Last edited:
Those taps suck. Cut, splice, solder, and shrink wrap, only way to go. Do it once. Do it right. You can get a cheap solder iron to get yourself started.

What he's saying is you can switch power, or you can switch ground. By switching ground, you only have to find a decent ground near the switch (easy to do) instead of splicing into 12v in the cab. When switch is off, there is no ground, so circuit is broken. Flip switch, ground is made, circuit is complete, lights turn on.
 
switch the ground, always switch ground in a vehicle. 2 benefits to this. 1) less current going through the switch itself if it's on the ground side since you're after the circuit load, and 2) if something goes wrong instead of a dead short you just ground your circuit just grounds and turns on whatever it's hooked to instead of creating a dead short and burning things.
 
To add to that, rather than soldering and using heatshrink, use a good ratchet crimper and splices like Raychem DuraSeals. Then use a heatgun to shrink them down and they will never, ever let water in to corrode your wiring.
 
In the harness they sent me 86 goes to the ground and 85 goes to the switch and 87 goes to the light. So I swap 86 and 85 so 86 goes to the battery as a 12v on source and then ground 85 after the switch?
 
85 and 86 are interchangeable on resistor-snubbed relays. If you have a diode-snubbed one it actually matters which one is grounded. Those are uncommon though, most auto relays are resistor snubbed.
 
Another hurdle. The switch that came with the harness has three wires. Not two. A white wire that runs to the relay and red and black wire. Also the light is grounded at the relay so I can't just swap 85 and 86.
 
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