I have a vintage 6volt vehicle and have installed a "helper" fan on the radiator, controlled by a temperature switch. This works well, but it's quiet and I can't hear when it's running, so I installed an LED indicator lamp inside the vehicle to remind me to watch the temp gauge when the fan is running. I didn't anticipate that the fan, when OFF, will generate a little DC power of its own due to the air movement when the vehicle is on the road--this lights up the LED to a low level, but I'd like to eliminate that side effect. Here's a diagram of the circuit:
**broken link removed**
Where can I put a diode in the circuit to stop the backflow of current, what size diode, and polarity?
Thanks!