Tapping into headlight wiring

[Ozjeeper1]

I have a JLU Rubicon that came with factory LED headlights and AUX switches.
Installing an auxiliary LED light bar .
How and where is best to tap into the high beam so the light bar switches on when I hit the high-beams ? and switches off on normal beam? I ask in case LED is different to the older Halogen where you tapped into the power at the light
Thanks

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[Dagwood]

I would wire it to the aux switch but if you want to do high beams I would use a meter to find the high beam wire at the front right headlight and use a diode and relay to give output, you don't want to draw power from headlight circuit. I said front right because that is the side the aux switch wires and battery is on to finish wiring.

Another way to get your high beam way and my aux switch way would be use a five pole relay so it would work with high beam and aux switch.

 

[Dagwood]

The wiring of the five pole relay would be

86 to your high beam wire and I would suggest a diode in line so the jl sees no resistance change.

85 to ground

87 to 12v fused

30 to positive wire of light bar

87a to aux switch wire.

This would trigger light with high beam and aux switch. Again I would wire it to aux switch only if it was mine.

Also if you do go your way, use a waterproof relay and harness to make for better end result.

 

[roaniecowpony]

As Dagwood stated, tap the high beam signal to trip a relay. You'll need to run power from a fused power source to the relay power circuit side as well. You should be able to find an open unused power source on the fuse panel.

My recommendation would be to run the high beam signal wire to a switch (your Aux switch), then to the relay. What this does is allows you to use your high beam headlights normally without the light bar, then, when you want the light bar to work with your high beams, engage the Aux switch. The light bar will come on and off with the high beams only when the Aux switch is engaged. The lightbar won't work without high beams, but you will be able to use high beams without the lightbar. You get more choices of light use and if you get stopped at some state safety check, you won't get popped for the light bar coming on when they check your high beams.

 

[Dagwood]

Roaniecowpony's idea is good idea. It would require two relays and one diode.

First relay

86 would be high beam wire with diode in line.

87 12v fused

30 to light bar.

85 to second relay pole 30

Second relay

30 to first relay 85 pole

86 to aux switch wire

85 ground

87 ground

This would result in high beam triggering light bar only when aux switch is on and operate regularly when aux is off.

 

[Mad Hatter]

I too plan to eventually install some auxiliary lights controlled by the AUX panel and operate with high-beam only.

Over the years I've installed fog lights with relay, etc., so I understand the a to b above. Most of us would agree that today's computer-loaded electrical systems are much different than the brute force 12 volt systems of 40 years ago. The diode addition represents a bit of modern fine-tuning. I am not an electronics engineer, but I've picked up just enough along the way to get myself in trouble. Diodes are polarized, from my understanding and look-up (see image below). Which "end" should one tap into the high beam wiring? Any recommendations from easily found sources? Thanks!

 

[Dagwood]

I too plan to eventually install some auxiliary lights controlled by the AUX panel and operate with high-beam only.

Over the years I've installed fog lights with relay, etc., so I understand the a to b above. Most of us would agree that today's computer-loaded electrical systems are much different than the brute force 12 volt systems of 40 years ago. The diode addition represents a bit of modern fine-tuning. I am not an electronics engineer, but I've picked up just enough along the way to get myself in trouble. Diodes are polarized, from my understanding and look-up (see image below). Which "end" should one tap into the high beam wiring? Any recommendations from easily found sources? Thanks!

Basically if you hold a diode with the stripe on the right side, it will let positive to flow from left to right but block flow in reverse. Opposite with ground, it would flow right to left but be block flow left to right.

So in this situation you would have the high beam wire go in on left side and right side to relay.

It may not be needed but what we are talking about I have not done so we are talking theoretically not practical application. It certainly wouldn't hurt.

 

[mal]

Just revisiting this discussion. To make sure I understand...

On a JLUR with the Aux switches, could you use the output from one of the 40A Aux switches (Aux 1 or Aux 2) as input (pin 87) to the relay and then trigger the relay (pin 86) using input from the highbeam? So, I single 4 pin relay with diode protection. For good measure, include an inline fuse between the Aux 1 output and the relay.

Thanks

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