Bare with me on this.. I have each of my fans on switches. Each switch is palced on the ground lead coming from the relays. Instead of buying a lighted rocker switch I want to add an LED, please dont ask why, just making some custom changes to the interior right now.

This is what I know ( I think I am doing this right) I out a DVm on the ground and see that the voltage is about 13.3 volts while the car is running... and the mA is about 166.8 to 169 mA.....

I can not just add the LED into series with the swtich and make it light. When I add the LED in parallel after the switch going to ground, the lead lights up when the ground for the fan is not touching, but as soon as the wire from the switch goes to ground the LED turns off. Guy at Radio Shack said because the ground from the switch for the fan is drawing more amps and therefor not enough to light the LED....the LEDs I was using was rated at 12v, 15mA and even tried a 12V, 50mA.....no luck.

UGH, electronics I do not know very well at all.


My goal is to mount the switch in a location where it is not to be seen but yet add an LED to the center console to show that the switch is on and the fan running..... simple I thought.

Can any help me in this?....

Thanks

 

Well when you close the switch and the LED is wired in parallel you effectively "short out" the LED and the voltage across its terminals will be 0. That's why it won't light up. If it's in series it'll probably burn out pretty quick and might not cause the relay to engage.

Best way to do it is by bring in an additional wire from an +12V source. (one of your bulbs in the console, switched ignition power, your CD/TAPE player, etc etc).

The negative lead of the LED will go to the wire coming from the fan relay, while the positive lead will connect to the +12V source THROUGH a 600 ohm or so resistor. (buy em at Radio Shack). This way when you turn the fan on and the switch is closed the LED will light up.

Let me know if you have any more questions.

 

Thanks for the responce, worked like a charm