Powering Light-bar with High beams

[BSJBSJ]

I'd like to install a LED light bar/s to the grill.  Would there be any problems tapping into the High beam wire harness?

 

Only wanting them to illuminate when the High beams are on. Not super high draw MEGA lights either. Just some additional lumens...

[lowspeedpursuit]

Good practice in general is to run accessory loads directly from the battery or fuse block, through a relay whose control pin can do whatever you want. Whether the high-beam circuit could power the load directly depends on the draw of the lightbar, the existing draw of the high-beams, and the size of the wire. I wouldn't assume it has the overhead, and I wouldn't install additional lights that way personally even if it did.

 

Even if I tapped the high-beams for control, I'd also switch it, if only for legality reasons.

[Don Ridley]

Use a relay. The vehicle ECU may throw a code if you add a load to the high beam circuit. Plus headlight power may be modified by the ECU (pulse width modulated) and the LEDs may not work. You can test everything or just use a relay and tap into the fuse block on the front of the battery. See my post on adding high power loads using this fuse block.

[Fifty150]

Use a fused relay.  The fuse will be a part of the relay, so no need to install a separate inline fuse.  These are available from most of your electronics or auto supply sources.  There are many brands.  Buy one with a harness if it makes it easier for you.  

 

 

 

 

Change the fuse to an appropriate size.  No matter what the seller claims for watts and lumens - it's usually not accurate.  While the item description may say 240 watt or whatever, it's probably less than 60 watts, or 5 amps on a 12 volt system.  Whatever you buy, test it so that you can install it with the correct fuse.

 

 

 

 

For something like the below shown wiring harness, pole 86 is positive, and pole 85 is ground.   There is a coil in the relay.  These poles are for either end of the coil.  On some diagrams, you will see 85 as the power, and 86 as the ground.  It doesn't matter.  As long as power goes in one, and the other end grounds, it energizes the coil.  This is what trips the relay to turn on.  You will tap your high beam wire and connect it to either 85 or 86, and gound the other pole.

 

Pole 30 is known as the Common.  That is the pole which will connect to the battery for power.  On a fused relay, the fuse will be on pole 30.    

 

Pole 87 is the Normally Open pole.  Often referred to as "N/O".  This connects to your lighting.  The circuit is not connected to the battery for power, until the coil is energized.  Once you turn your high beam on, the coil will connect the power from the battery to the lighting.

 

Don't forget to ground the light bar.  On a lot of diagrams, you will see that the the light bar ground and relay ground can be connected together.  That is correct.  It is safe to do that.

 

 

 

 

 

 

 

Edited October 5, 2022 by Fifty150

[Fifty150]

 

 

This is the light bar on the front of my Transit Connect

 

 

[BSJBSJ]

You say crazy stuff.

[Double Nickels]

 

 

Every day in America, I see trucks with all sorts lights on bumpers, grilles, A-pillars, on the roof, on the roll bars........ I believe the spirit of the law, and usually the letter of the law, applies to how you use them.  If you're just driving down a public street or highway, and you have them on, then there may be cause for a traffic stop and conversation.  Every state has different regulations in regards to how you mount them, aim them, and when you can use them.  In some states, if the lights are not higher than the headlights,, and the beam is aimed so that the useable portion of the light beam is on the road surface, the lights could be driving lights or fog lights.  Driving and fog lights are always aimed on the ground, so that you can see the road.  The problem usually is with high powered lights pointing straight, or slightly upward, directly into the eyes of oncoming traffic.  Any light mounted above the headlight level is definitely an offroad use light.  You don't aim these on the road.  You aim these into the horizon, so that you can see above the road level - trees, animals, people on the street, down a dark alley, etc.  Common sense tells you not to use it on a public road.  If you really want the police to leave you alone, don't turn the lights on, or cover them.  Different types of covers are produced for light bars.  You may even have seen police cars with the rooflights covered.  Or you can make your own.  Some fabric and velcro.  Or a t-shirt with zip ties.  Or you have a tailor make a professional looking cover with straps and snaps.