smallest pilot light?

Looking for a very small, no bigger than 4mm diameter to indicate when current is flowing through a circuit. I have the wiring scheme worked out but need the hardware. Naturally it'll be 12 VDC. This will be mounted in the dashboard heater control unit of my Ford E250 van. it would be nice if its not too bright for night yet visible during the day. Mounting isn't an issue since I can modify my control unit without any problems. Thanks in advance! J W

a 3mm LED? Wire a 1K resistor in series with it. If it is too bright at night increase resistance until it suits your needs. It wouldn't take much to install a relay on your parking lights to have the LED "dim" when you turn your lights on. This could give you two different brightnesses.Kevin Pierson

^^^^This is pretty much what I was thinking---any help with the resistor values or wattage ratings? What about the LED's themselves---any idea where best to begin looking for something like that? Thanks!