I know nothing about LED's. I want to know if you can check them for continuity as you would a regular bulb.
I have a license plate light with 3 LED's in a row. When I check it with the continuity meter I get no signal between the hot and ground wire so I assume it's bad even though it was new in the package. Am I right?
Also, anyone else had trouble with LED lighting? The light is called a "Step light" sold by Signal Dynamics. Ted's fender eliminator kit uses them, or at least did when I bought his kit in '08. The package claims "100,000 hours life", and "made to resist vibration". The original light with the kit lasted about 2 months and went out completely (all 3 LED's.) The replacement lasted until a few days ago, same thing, all 3 are out. I had bought a spare a few years back just in case they stopped making them. So I go to install it and it doesn't work. My same continuity check says it's bad...straight from the box. I doubt Signal Dynamics will give me a credit but I'll call them in the morning.
I ordered 2 more so I'll have a spare but wonder if I should look for something else. Problem is I have the 2 holes drilled for the light and may not be able to find something that will go over the holes. Besides, why would someone else's LED last any longer?
I may try to add a thin layer of dense foam between the light and body but it would have to be pretty thin and I don't know if it would cut much vibration. One other thing that kind of pisses me off is all 3 of the taillight posts for the mounting screws are cracking. I never over-tighten plastic stuff. So it bugs me more I have to keep disturbing those screws because these damn lights aren't lasting like they claim .Jeez, they can't make anything well anymore.

An LED is a diode. A diode only allows electricity to flow through it in one direction. Have you tried reversing your leads?

I am using a bike master LCD LP lamp. Works great and is bright as shit. Cheap too.

* Last updated by: nasty on 10/13/2013 @ 1:19 PM *

I connected the wires same as before. The 14's red wire to the LED's black, and the 14's black and yellow stripe to the LED's white. If I tried reversing the leads, thinking the maker assembled them wrong, would that blow a fuse?

No. The led will stop the flow of electricity if its backwards. Can't hurt a thing.

1. Cunking Junking made? Spank the USA company when you call. Made in USA or no way hose say can you see, buy the nasty has a point. This is a one way wattever.

2. Speaking about watts, eye over E and all that is why do you think they are blowing? I = amps and to get it write, you'll need a pencil, paper, and a calc. Add up your watts. So if there are 3 LEDs that have I have no clue what watt rating they are, say they are in need of a resistor bleed?

3. Might this save the bulbs from blowing out? It may have a mini-diode that if you look at the package of a bunch of them, the loner leg is the (+) side and the short leg is (-). So if you use ohm's wheel, you add up the watts of each bulb, do a little math and see if you can figure out what resistance it needs? I've played around with LED's off a computer part. Threw a resistor at it and could change the color of the bulb. Tied one less resistor in line and the color changed.

4. Variable. So WATT it might need is a resistor on the hot side of the wire that ties in to the (+) leg. So the setup might look like:

1. Battery
2. Wire out of the (+) side of the battery.
3. To fuse.
4. From fuse to a resistor off some abandon computer component hanging out in the garage?
5. From that resistor, either a wire or solder the (+) LED leg to that wire.
6. From the (-) LED leg you attach the next LED's (+) leg to the first (-) out, and so on till you have a string of LED's.
7. From the last (-) leg you check for continuity down the line, so that meter prong goes to ground side of the battery, you match the math number at the meter to the paper's number.

Thanks for the replies.
nasty, I tried swapping the wires and the replacement light I had worked.
I could swear the wires are supposed to be hooked up as I said earlier but maybe I wasn't paying attention when I cut them. You would THINK that the LED's white wire is a ground and would go to the 14's black with yellow stipe? Seems strange connecting it to the 14's red wire. Anyway, I searched the internet for instructions but found none for Ted's kit. Like an idiot, I must have tossed his instructions. Checked out a few You-Tube installs on other bikes but every bike uses different colored wires so there was no help there. Some showed owners connecting orange going to grey, stuff like that.
Only other possibility is the new LED was wired backwards? I don't know but I'll try to find out if this is my mistake.
But it works and I really appreciate your help. Saves me a phone call begging for a credit, plus I can get the bike back together today. Thanks to you too Hub. I hope to get decent life out of this light but if not then I may have to look into this resistor thing you mention. Hope not.

Most meters have a diode checker mode. It takes 0.7 V to make a typical diode conduct, and it will only do that in one direction. 3 diodes in series will require 2.1 V to conduct. Checking them for continuity using an Ohm meter won't tell you much. The ohm setting doesn't push much current.

Oh, and 3 diodes in parallel will take 0.7 V to light.

Yeah if you don't have a proper resistor in line with the LEDs they will burn up quite quickly. It's about controlling the voltage/amperage, one or the other, don't remember right off the top of my head at the moment.

Lets say we use 4 LEDs out of a computer. We know that this bulb needs 5v, not 12v. We want to bring the bulb back to 5v or under for longevity.

So if we have 4.8 watts @ 1.2w each x's 4, we need a 5 ohms resistor in parallel to bring it down to 4.89v. I cheated. I used an ohm's law calculator, plugged in resistances because I knew my watts, and watched the volts drop until I had my resistor number.

* Last updated by: Hub on 10/13/2013 @ 7:25 PM *

OK. Guess I'll contact Signal Dynamics and find out how many watts my LED light makes. I hope they can tell me what resistor I need.
Do I just splice in the resistor before the light?
If the resistor is correct, the light will still be as bright?

You are opening up a whole can of worms here now. You need to know the wattage, voltage, resistance, amperage, voltage drain/loss, and a couple other magic numbers and a couple formulas to factor in the exact resistor you need for an LED. Hopefully you talk to someone intelligent when you call that can tell you right off the bat what you need for a resistor. Are we in series or parallel? That matters to for placement of the resistor. In believe the resistor goes to the hot side(+) when wiring them in. You will lose some of the intensity of the brightness but that is actually the brightness in which it is supposed to be after it is properly wired in. LEDs are simple until you start getting down to the nitty gritty, then they become quite complicated when you start getting your numbers together and doing the math.

I just found my notes for the LED formula in my toolbox

Powers source - voltage drop(Vf) = V
V = I(mA) * R = A

mA needs to be divided by 1000

The rest if the formula is usually on the LED package.

It's been awhile since I used this formula and don't know what anything means right now but this is exactly what I have written down. Usually the numbers you need to fill in the blanks are on the back of the package when you buy LEDs in a package. It will make sense to me next time I need it, usually does.

* Last updated by: nasty on 10/20/2013 @ 8:42 PM *

Are you certain you even need a resistor for your LP light in the first place? I would hope its all been done proper when they sent it to you, but you never know. Maybe it's how they make an extra buck off ya.

Thanks for the replies.
I contacted Patrick Ng at Signal Dynamics. Helped me out the next day. He said the LED I bought has micro-resistors already installed. If I added a "large resistor" as he called it, it would decrease the amount of light. So I don't need to add a resistor.
Earlier replies made me wonder if the LED's short service life was related to resistance. Signal Dynamics claims the life is 100,000 hours but I'm sure not getting that. They also say they're made to withstand vibration.
I'm buying 2 spares in case they stop selling them. I think vibration/rough roads is what damages these small lights, especially in the tail area. This time I cut out a piece of foam about 3/8" thick and made a "foam spacer" in hopes of cutting some vibration. After tightening the small screws the foam compressed down to about 1/16" so I'm not sure how much it will help.

There is only 8760 hours in one year.

Right. That's why I was wondering if something is shortening the life.
I think it's vibration. Not a whole lot I can do about it other than what I'm trying now. Maybe this one will last.

led not effected by vibration.
Likely voltage issue. Is it wired to good ground on the bike?

Signal Dynamics claims the LED "Step Light" is specifically designed to withstand vibration.
I assume the ground is good. My tester says the ground is good. The tail light goes to the same ground. No problems ever with my bike, other than this aftermarket light.