Almost 3 years ago, I installed a Signal Dynamics Heads Up voltage monitor LED on my 2007 Vee. Whole saga here, if you're bored or need a sleep aid:
The device has worked perfectly since then...so, of course I had to screw things up by accidentally breaking it.
This likely happened last week, when I was installing a new 12V socket under the cowling. I must have yanked on the wires harder than I realized. A few days ago, I noticed that I was only getting a "blinking green" indication for a few seconds, then nothing, with key turned on but before starting the engine.
If you own one of these things, you'll recognize that this is not normal behavior. What should happen is the LED blinks green, then steady amber, then steady red, as the battery is powering the lights, instrument panel, and fuel pump all by itself. The LED cuts out during actual starting, then stays a steady color (green, if all is normal) with the engine running. Then goes back to amber, then red when you kill the engine but leave the key at run position (in which case, my broken LED is now turning off).
The LED was still showing steady green with the engine running, but I didn't trust it due to the pre-start behavior.
Inspection reveals that I have broken one of the LED's three terminals clean off. There's no way to fix that - it's time for a new LED. No charging system problems. Battery is sitting at a healthy voltage while at rest, charging voltage is right where it should be.
Naturally, the LED's flimsy, plastic panel mount bezel broke in the process of taking it out for the inspection, so I need a replacement for that too.
Here's the happy ending: I called Signal Dynamics, explained the situation and asked for help buying a replacement LED. They're sending out a replacement LED, at no charge, pre-wired and with a new panel mount bezel. Even though it's way out of warranty. I could not ask for better customer service.
I would have happily paid for a replacement LED. But they saved me both $ and effort.
FWIW, if you want to build your own voltage monitor device, don't bother looking for 3-color LEDs that do red, green, and yellow. They seem not to exist, or would be a custom order from an LED manufacturer. I think what Signal Dynamics is actually doing is using a 2-color, red and green LED, mixing red & green modes to make yellow. Which is clever and elegant.