I'm building a simple circuit based on a relay and transistor to switch a fan for use on my boat. A digital pin from an arduino is connected to base of an NPN transistor, the emitter to ground and the collector to the ground pin of the relay. The circuit does not properly switch. However, if I short the emitter to the collector, the circuit functions fine (although not triggered by the pin). I took out a multimeter and the voltage from collector to emitter reads 0.02v. Is this enough to throw off the pin? Why is there any voltage at all?
EDIT: Extra info. 5V relay, 2N3904, pin from micro > 1k > base | 10k Pull down I do have a protection diode across the coil.