Dual Headlight Wiring

[sonny8l3]

Hello, I just replaced my old sealed beam headlight with 2 single LED lights. Each light is a 2 wire unit, hot and ground. I wired them to my existing headlight control (standard handlebar control housing). I wired one hot wire to the low beam hot wire to the switch. The second light I wired the hot wire to the high beam hot wire. The ground wires from each head light I wired to the switch ground wire. When I turned on the low beam, the correct light came on. I was tickled. When I put the switch to high beam, the first light went off and the second one came on. At this point I could have hit myself in the head with a big stick. They work just like I wired them. SHOOT! The original idea is to have the low beam light on by itself and when I turn on the high beam the second light comes on AND the first light STAYS on. Now that I've got them all mounted, I don't know how to change the wiring to work the way I intended. Any help will be greatly appreciated.

Thanks for your tine,

[Gorilla]

A relay might be in order you would wire it to feed both lights when High Beam is selected. And leave the low beam alone. If you want to add a diode in the low beam feed in front of the relay feed if you were worried about 12 volt back feed but I do not think it would be necessary. Just my feed on this an idea only. your call.

[vwbug72501]

It is important to make sure that the forward current rating of the diode is greater than the operating current of the lamp or it will burn out. If you don't have that information then you can determine the current draw by placing a multimeter in the current range in series (red lead to +12 and black lead to lamp red lead) with the lamp and connecting the circuit to your battery. Always start at the highest current range and move down.

Hope this helps.

[vwbug72501]

This assumes LED lamps. They don't draw nearly as much current as conventional bulbs.

https://www.amazon.com/20-Pieces-15S...6-f96e7b0f409c

Here's a suggestion. Check out reviews.

[sonny8l3]

Thanks folks. I probably should've mentioned that I am mechanically declined. Y'all are way over my head. I'm hoping for a simple solution, like "add 1 wire here". If not, their going to be ok as is. Thanks for your time

[vwbug72501]

Thanks folks. I probably should've mentioned that I am mechanically declined. Y'all are way over my head. I'm hoping for a simple solution, like "add 1 wire here". If not, their going to be ok as is. Thanks for your time

Sonny, stop beating yourself up. We all come up short on something. That's why we have the forum.

I looked at the diode specs in the link I posted and in the reviews there was a fellow using them in a SUV headlight application and they worked fine. These are 45 amp diodes so they should work for incandescent bulbs and LEDs. Think of them as "one way" wires. The schematic symbol for them shows an arrow (anode) pointing at a plate (cathode). When you have + voltage at the arrow end and ground (negative voltage) at the plate end, it acts like a straight wire. When you have negative voltage at the arrow end and positive voltage at the plate end, it acts like an open wire.

So when you have the Low beam on, the +12v goes to the low beam bulb but does not go through the Diode "wire" because the plate is at 12v and the arrow is at 0v and it won't conduct. Low Beam only.

When you have the High beam on, the +12v goes to the High beam lamp and goes down through the diode "wire" because the arrow is at +12v and the plate is at 0v and it conducts and becomes a straight wire. High and Low beams!

The plate (cathode) of the diode is the silver stripe on the end of the body in the pictures. $7 for 20 of them is pretty cheap to become the envy of all your friends for your amazing new found electronics aptitude !!

Seriously, if you can build a trike, you can do this too. It's really not rocket science and we're here to help.

[sonny8l3]

Hello Tom, I quit beating me up years ago. There are several things that I am very good at, self honesty is one of them. And working on anything that runs on gas or diesel is not even close to the list. But thanks for the info.