Double Check my Turn Signal Schematic?

[stopintime]

Fill more gas? 

[Howie]

Does the fuel light stay on when you put the bike in gear?  If it goes out in gear you are grounding through the neutral light and a diode will fix it.

[Artful]

Not grounding through anything else from what I can tell. I hooked up a multimeter and the leads showed 12v from pin 26 (12v constant) and pin 20 (fuel "ground")...

Also, I topped the tank off just to be sure, light still on.

[Duck-Stew]

The sender in the tank is a two wire proximity swith which are notoriously leaky with voltage.  Not enough goes through to light a regular bulb & I'm sure the gauge board compensates for the leak.  It would light an LED though...

Or, you have a bad sending unit...

[Drunken Monkey]

The sender in the tank is a two wire proximity swith which are notoriously leaky with voltage.  Not enough goes through to light a regular bulb & I'm sure the gauge board compensates for the leak.  It would light an LED though...

Or, you have a bad sending unit...

That's my theory too. If it's "leaking" (measure the ohms on the sensor with the tank full, if it's not zero, it's 'leaking') use a zener diode. A zener diode blocks the flow of current in one direction, unless the current goes above a certain voltage. 9v should do the trick to keep current from flowing to the light until the sensor's resistance drops below a certain threshold.

Mind you... yours normally lights up when you first turn on the bike, correct? This points to some weird combo of the dash / ECU doing something in concert with the sensor. in which case you'll probably need a relay to make it work. 

[Artful]

With the tank full I was getting like 40mV from that lead to ground in the time period that the stock dash illuminated the fuel light. So definitely not enough to light anything, but if that is all that comes off that circuit when the lamp lights I could possibly find a relay that would trigger with that voltage to complete a 12V circuit with the LED. If the voltage increases as I remove fuel I can just wire in a zener or something that won't allow flow until it hits a certain voltage then run that through the indicator. Calibrating that voltage will probably leave me stranded on the side of the road once or twice

When this gets done and works, someone is buying me a beer (and I will pass that beer along to whoever helps me figure this damn thing out )

[Drunken Monkey]

So you're seeing 40mV off the two leads, and then seeing that drop to 0v after a bit of time?

If that's the case you should go with a small relay, as you suggest. just make sure the relay can be triggered by a tiny voltage.

If you're seeing 40mV off the two leads all the time, then test to see what the voltage is with the tank empty. That'll give you all the answers you need to wire this up. Somehow.

[Artful]

So I'm officially at an impasse. Measured voltage from Pin 20 (fuel lead) to ground and got essentially zero change from full to empty. Drained the tank a bit then ran the motor until the factory light came on, pulled the gauges and measured without turning the bike off, no change in voltage.

So the answer is magic. Magic turns on the factory fuel light. Stew talk to me about this switch, what leads should I be testing, and what should I be testing for? Voltage? Resistance?

I'm above my paygrade here gents, any and all help is appreciated.

[Ahks]

i know i said i was gonna stay outta this...

Whats the chance of it not being voltage related but signal generated? The electrical geeks know more about what I'm suggesting than I do. So I'm ducking out again

[Artful]

Distinct possibility. To compound matters, after the stock fuel light comes on once, you kill the bike and restart, it takes a while to come on again. That's normal and has been like that since I bought the bike. So like I said... it runs simply on magic.

[stopintime]

Distinct possibility. To compound matters, after the stock fuel light comes on once, you kill the bike and restart, it takes a while to come on again. That's normal and has been like that since I bought the bike. So like I said... it runs simply on magic.

Mine too. So, the low fuel light can't be a steady flow of electricity? Maybe the ECU gets a steady flow, but needs some time to decide that it's time to tell you through the light - which also avoids a flickering light when it's getting close. If I'm right you need to connect closer to the tank, not after the ECU. (be careful - I have no clue - just thinking out loud)