My 'Ingenious' Fog Light Wiring

[CamaroEric]

People are always looking for ways to wire fog lights so that they're off with the ignition. This wiring applies to the NC and just about any other bike with an H4. It can be modified for just about anything. I have no idea how the wiring looks on the newer bikes with the LED headlight since I did this on my 2012 NC (and some other bikes).

In short, I am running my LED fog lights directly from the power (in parallel) going to my headlight. I tapped off an H4 extension and sent the power to a 3 position SPDT switch (ON-OFF-ON) on the handlebar which offers 3 options:
1) Aux lights on when LOW beam is on.
2) Aux lights OFF.
3) Aux lights on when HIGH beam is on.

The 'ON' positions are tapped to the High and Low beam wiring separately with the center (which is typically the 'power in') actually supplying power to the aux lights.

Now there may be concerns with power - so verify this depending on your aux lights!

So let's just say you're running a standard 55/65 watt H4. At 65 watts when the bike is off (11.5V) the max draw is 5.65A. With a 10A fuse as stock, you have 4.35A remaining *technically* allowing another 50W on the circuit. I wouldn't do it, but my lights are only 15W, mostly so people see me coming, but I do get some ditch lighting out of them. That's another 1.3A, and I am totally fine running 6.95A (drops to 5.7A at 14V) on the stock wiring through the stock 10A fuse.

If you have bigger lights drawing more wattage, you'll need to send the output to a relay with appropriately sized wiring. A quick check shows that some Harbor Freight LEDs are claiming 95 watts! 8.26A at 11.5V! This will definitely need separate fused battery power. Relay wiring is all over the internet and there are a few ways to skin that cat.

So here are some pics of the wiring and components. Keep in mind these wire colors are PROBABLY NOT correct. I'm winging this from memory.
I will also add the disclaimer that this is for information only and I am not responsible for any wiring experimentation you do with your bike or other vehicle!

Thanks for reading...

 

[davidc83]

You have a link for that toggle switch?

 

[CamaroEric]

You have a link for that toggle switch?

I bought this one but it appears to be out of stock.
https://www.ebay.com/itm/114911622766
You should be able to find an identical one from another seller in the 'similar items' links.

 

[davidc83]

Thanks, I found it on Amazon...

 

[mackinac_rider]

A couple things. 1) Incandescent or halogen lights that have a relatively fixed resistance (which they do over small variations in voltage) will have more current running through them as voltage rises, not less. V=IR and P=IV. So the power that a 55 watt bulb consumes isn't fixed at 55 watts. Both current and power will be higher at 13.5 volts than at 12 volts. LEDs are a whole different thing, so ignore what I just said for LEDs. 2) Many times LEDs are rated in "incandescent equivalent watts", meaning those Harbor Freight lights might burn as bright as 95 watt incandescents but actually use a lot less power. I could be wrong on that, but 95 watt LEDs would be insanely bright.

 

[Rydinon]

Circuit ampacity is a bit more complicated than the way you described it. I found the wire sizes used on my Honda ST were surprisingly small. Clearly, they were sized for the load, and not necessarily for the fuse. Rather than add loads to the original harness, I chose to add a relay and auxiliary fusebox, and used your green wire to trigger the relay.

I admit to not ever having seen the inside of an NC, but I doubt Honda spent any more money on wire sizes than they had to. All this said, adding a one amp load is unlikely to create a problem.