View Full Version : wiring LED oil light.

11-15-2014, 8:57 PM
So when I made the wiring harness on my ironhead I made it about as basic as possible. I never ran an oil light but now that I have a newly rebuilt motor I think it's a good idea. I have a two prong LED and I'm wondering how to wire it in as an oil light. Is it as simple as running the wire to the sender and to the ignition? What about a ground? I'm pretty clueless when it comes to electrics.

11-16-2014, 3:50 AM
Run your hot wire from the ignition switch to the LED positive side, and run a wire from the sending unit to the negative side of the LED.

11-16-2014, 7:10 AM
Does the LED have a built in resistor? If you just got an LED from radio shack or something, like this:


It's only a 4 volt LED, and it won't work without adding a resistor.

There are lots of 12 volt LEDs with built in resistors, but they generally have wires, not prongs.

What ^^^slim said is correct. Note that LEDs are one of the few electrical items you will find on bikes that have directional current flow. The D in LED stands for diode, which is sort of like a one way valve for electrical current.

11-16-2014, 9:30 AM
Thanks for the replies. The LEDs I have look like the ones above. The guy who gave them to me said they're the same ones he used for his oil light. Is it possible they would be 12 volt? I wish I could find the thread on here where I discussed it with him but since the search function got all fucky I can't find anything.

11-16-2014, 9:30 AM
Why not just run a gauge off the front of the oil pump ?

11-16-2014, 10:29 AM
Simply test the led with a 12v batt. You'll know if it works w 12v and which leg is +

Most oil gauges are grossly inaccurate, aren't usually self illuminating, not usually mounted where you can see them while riding and with low press volume type systems are a mute point at operating temp. If zero to three pounds at idle is good then what's the point?
Basically they don't warn you when/if there's a loss of press. An Idiot light placed where you can actually see it while riding does.

Note, with hydro lifters you can hear a loss of oil press, so I don't feel the need for a gauge or a light. But with noisy solid lifters a light is a good idea.

11-16-2014, 11:56 AM
I put an led oil light and a neutral light I had to solder a resister in . there are websites tha tell u what resistance to use . At first I blew a couple bulbs so I went w a more resistant resistor. I blamed it on shovel electrical fluctuations

11-16-2014, 12:40 PM
Sky, you can get a low pressure reading gauge. Most are 60 but mines 30 and clearly shows increments up to 20 lbs. Its accurate enough to show 12lbs when the oil is cold and 9lbs at operating temp. Is it truly 9lbs? Who knows, but i know when the needle is on 9, everything is good. I have mine mounted in view from the seat via grease gun hose. It threads right into the pump. I do see what you mean about the light but I prefer a gauge. I know the OP asked about a light but I just thought I'd throw that out there. I do think the gauges you see on the rocker shafts are a joke however.

Also something to consider is lights/electronics are prone to failure. A gauge is pretty durable and dependable.

11-16-2014, 2:48 PM
My reason for going with the light is mostly what Sky said. I have the light mounted right on the bars so I don't have to keep looking down all the time.
Any recommendation on a resistor? Like I said, I'm really clueless when it comes to electrical stuff.

11-16-2014, 3:28 PM

11-16-2014, 4:55 PM
Here's a couple more;

I used the with a resistor: http://www.allelectronics.com/make-a-store/item/ind-13r/5mm-ultra-bright-led-w/metal-case-red/1.html

http://i232.photobucket.com/albums/ee110/Apelike1/BF/Idiots.jpg (http://s232.photobucket.com/user/Apelike1/media/BF/Idiots.jpg.html)

11-16-2014, 5:00 PM
Sweet, thanks guys!