I asked a few months ago on how to add a LED to a switch to indicate when the switch is off. Sgtwookie set me up with a plan here.
http://forum.allaboutcircuits.com/attachment.php?attachmentid=14037&stc=1&d=1259601684

This is the post.
http://forum.allaboutcircuits.com/showthread.php?t=30849

I built it on a breadboard and it work great. I had a red LED for off and a green LED when the the light was on.

I then built it into my dashboard for my motorcycle. It worked fine while testing it out.

I just wired into the motorcycle and it doesn't work now.

The switch will work to turn the headlight on and off. But the green LED is always on, and the red doesn't come on at all. I tried it with the test setup again and it did work.

Any idea how I should trouble shoot this? I can post a wiring diagram for the motorcycle if that will help. I think I might be getting some power back feeding and might need a diode.

Todd

 

Provide a good picture of what you have done if you can. You most likely made a wiring error.

 

Resistor too small?

 

I'll bet the red LED is shorted.

Replace the red LED, and increase the resistor from 510 to 680 Ohms.

 

That was the problem. New LED, and 680Ω rewired on the bike and it worked.

I should have posted this first before wasting all the time I did trying to figuring it out on my own.

The amount of knowledge on this forum is priceless.

Thanks to all.

Now back to my USB problem.

Todd