I refitted a 914 fuel level sender to my car today - it came with an aftermarket sender and gauge - and hooked it up to a 50mm VDO fuel gauge in the dash. The gauge has no low fuel warning light so I'm trying to figure out if I can wire up a separate LED to do the same job.

How does the original light work, I know it connects to the gauge via the black wire but does it also take power from the fuel gauge? Whoever wired the aftermarket gauge/sender butchered the harness at both ends cutting the black warning light wire to use as the gauge to sender wire (???), so I can't just unplug and replug.

Thanks
John

The sender works by grounding the wire that goes to it. I forget offhand if it has a ground wire attached to it, but if so it shorts the "warning light" wire to that ground wire when the float hits the bottom of the cylinder.

So the light gets power when the key is on, and it gets ground when the sender hits bottom. That turns the light on.

--DD

Great, thanks Dave, I'll give this a shot at the weekend.