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Light bar triggered with high beams

thomps33

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Anybody have an idea how to power a light bar when the high beams go on? I'm not sure how to do it with the newer canbus systems these trucks have.
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Unfortunately if you have the LED headlamps there is no trigger for high beam.
 
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thomps33

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Please don't install a light bar. It blinds other drivers and makes everyone else hate us for driving trucks.
Have you ever been to Alaska? Everybody has light bars. You can drive for hours in the dark without seeing another person and your life can depend on seeing a moose on the road.
 
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skierd

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Do you want your bar to have a second switch in the cabin as well, or do you just want it to come on automatically with the high beams?

For the latter, you’ll need a relay harness to pull power from the battery. On my Tacoma I used a posi-tap connector on the drivers side high beam positive and wired It to the switch terminal on my relay. Power came from the battery, ground to the chassis.

86 from your switched source, 30 from your battery with a fuse, 87 to the light bar positive, 30 to ground.

Ford F-150 Light bar triggered with high beams 1645205303963
 

UNIKRN150

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Do you want your bar to have a second switch in the cabin as well, or do you just want it to come on automatically with the high beams?

For the latter, you’ll need a relay harness to pull power from the battery. On my Tacoma I used a posi-tap connector on the drivers side high beam positive and wired It to the switch terminal on my relay. Power came from the battery, ground to the chassis.

86 from your switched source, 30 from your battery with a fuse, 87 to the light bar positive, 30 to ground.

1645205303963.png
This IS the solution.

I have my grill filled with single LEDs all wired exactly like this.

Bosch Relay. Summit Racing... Six bucks!

Ford F-150 Light bar triggered with high beams Bosch Relay
 
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thomps33

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This IS the solution.

I have my grill filled with single LEDs all wired exactly like this.

Bosch Relay. Summit Racing... Six bucks!

Bosch Relay.jpg
I’m familiar with relays and have used them in the past to do the same thing. Do you have LED headlights? I heard it doesn’t work with the LED headlights.
 

UNIKRN150

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I’m familiar with relays and have used them in the past to do the same thing. Do you have LED headlights? I heard it doesn’t work with the LED headlights.
No I don't but I can't imagine why it wouldn't work. You might need to use solid state relay though.

I'm not an electronics engineer but I have had to use Solid State Relays for projects in the past. I went to the surplus store, bought a bag of various 12v relays and wired them until I found one that worked. It turned out to be a Solid State. It worked when none of the others would…

Maybe someone here can tell us “why”.

In the project I'm speaking of, I used the Solid State relay to trigger the Bosch relay. That was 10+ years ago and it's still working today.
I might have something to do with isolating the relay circuit from your "triggering" (high beam) circuit.


(Ten Bucks)
Ford F-150 Light bar triggered with high beams Solid State Relay
 
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