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How to test a motorcycle headlight

How To Test a Motorcycle Headlight

For those wondering how to test a motorcycle headlight, this is the easy way to do it. It’s not just something you should be doing if your motorcycle headlight isn’t working, to test if the headlight is broken. This is also a great thing to do BEFORE you start installing a motorcycle headlight, and it’s super easy to do!

How to power a headlight directly from a motorcycle battery – all you need is:

  1. A motorcycle headlight (duh)
  2. A motorcycle battery (if you have any motorcycle made in the last 30 years, you probably have one!)
  3. Some wire with some conductive properties (commonly found on the floor of your garage behind your tool box, or here)

Since my battery was dead, I also used a Ctek battery charger to power things – I like the ones with a motorcycle mode and a car mode.

How to test a motorcycle headlight – video

Some people hate reading. I get it. Fear not, illiterates, I got you! Watch this video and you too can learn how to test a motorcycle headlight!

Click the little unmute button in the bottom left corner to unmute the video.
Watch this video!

Motorcycle headlight test walk-through:

There isn’t much to explain, but despite it being simple, there isn’t a lot on this procedure on the internet that applied to motorcycling as a whole, so we’re gonna change that!

Essentially the goal is to get the negative terminal of the motorcycle battery connected to the ground wire of your headlight. You know what? I’ll just make you a picture:

Diagram showing how to test a motorcycle headlight

Pretty self-explanatory, right? One wire from the negative battery terminal to the headlight’s ground (usually black) wire. One wire from the positive battery terminal to the contact for the headlight (test the high beam and low beam terminals individually).


I'm a motorcyclist, not an electrician

1: You’ll wanna use the proper nut and bolt that came with your battery for a tight and strong connection/contact on the battery terminal.

2: If your battery is dead this won’t work. My battery was dead. I kept mine on a battery charger and that worked.

3: Let’s be real. I’m a motorcyclist, not an electrician. The only thing I know about AC and DC involves a full grown man with a guitar dressing up in a school boy outfit. I’ve probably butchered the name of every single electrical component listed on this page. Whatever, who cares.


Overall, with an ounce of common sense, it’s an easy way to test your whether or not your motorcycle’s headlight is working. It’s a great way to troubleshoot your motorcycle’s headlight wiring harness too. For example:

  • Headlight works when hooked up to the battery but not when hooked up to your motorcycle? You’ve got a wiring harness issue.
  • Headlight doesn’t work when hooked up to the battery, or when hooked up to your motorcycle? Headlight is no good.
  • Headlight doesn’t work when hooked up to the battery, but does work when hooked up to the motorcycle? You’re just plain doing it wrong.

How did we even get here?

Well, last week I tried to install a new Daymaker style LED headlight on my Harley-Davidson V-Rod, and that kinda failed (see for yourself). Testing the headlight was part of how I fixed the problem this week.

The part where I beg you for your comments

*Ahem* If you have any questions or comments, please leave them in the comments section below! Things you can comment about:

  • If this helped you learn how to test a motorcycle headlight
  • If I used the wrong words/terminology or made a typo somewhere (Hello, Michael Scott!)
  • If this didn’t help you and now you burned your house down
  • Etc.

Overall leaving a comment just helps me to know that I’m not just out here talking to myself, so feel free to say hi!

About Adrian from YouMotorcycle

I started riding motorcycles in 2007, founded YouMotorcycle in 2009, and was working in the motorcycle industry by 2011. I've worked for some of the biggest companies in motorcycling, before going full-time self-employed in the motorcycle business in 2019. I love sharing his knowledge and passion of motorcycling with other riders to help you as best I can.


  1. Headlight doesn’t work on test or on motorcycle…. Its worse than that, it’s dead Jim!

  2. Where was this 4 days ago. My damn headlights still ain’t on and replaced bulbs and the melted damn plug. It’s definitely the ground thanks brother

  3. Forgot email lol

  4. My 07 Deuce has a white wire, black, and 2 yellow wires…… not exactly sure how to test my bulb???

  5. Is there any particular “don’t do” regarding a Road Glide headlight? It has internal circuitry and I don’t want to burn anything out. I’m doing a Road Rod conversion to a 2015 VCRSF with a 15 Road Glide fairing. Any help would be appreciated.

    • I’m not familiar enough with the Road Glide’s lighting to offer any specifics, sorry Ralph. I’ve seen one or two sweet Road Rod conversions on the used market over the years, one I still regret not buying to this day. Best of luck with your project!

  6. Hello. I have 2 wires back by the ic ignitor on a 2003 Kawalski zrx1200r that are just hanging out with nothing to connect. One is y/bk the other is bl/w The bl/w goes straight to the junction box, as it is called in the manual. It’s a fuse box. According to the manual, the y/bk is a fan motor switch. The fan motor works just fine. They look factory, so what the heck. I just bought this bike a short time ago. Thank you !

    • Grab a copy of the factory service manual for that bike, or at least a copy of the wiring diagram, and then you can see what those wires are supposed to be and take it from there.

  7. Best no B/S bike site and electrical site bar none!

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