A SF340 flight crew experienced an AVIONICS SMOKE light in-flight; but after a short time the warning cleared.

Narrative

About the time we leveled at our cruising altitude of 16;000 FT we got a AVIONICS SMOKE master warning message. I told the First Officer that I had the airplane and the radios and I instructed him to perform the emergency procedure for AVIONICS SMOKE. After he had donned his mask and goggles I had him take the aircraft and radios while I donned my gear. While I was donning my gear the AVIONICS SMOKE master warning went out. The AVIONICS SMOKE light was illuminated for about 20 seconds. I then informed Center that we had an AVIONICS SMOKE warning; the Controller stated that we should let him know if we need any assistance. We entered the procedure for AVIONICS SMOKE. After a few minutes we realized there was no smoke or odd smells in the cockpit. I had the First Officer call the Flight Attendant and ask if she could inspect the galley are for abnormal heat; smoke or smell. She informed him that she observed nothing abnormal in the galley area. I then had the First Officer fly while I removed the rubber grommet for the fire extinguisher port behind the Captain's head. I then put my nose to the port and smelled for anything unusual. I smelled nothing and we agreed to keep our gear on for a while to determine if the warning real or nuisance. We left our gear on for about 10 minutes and at this time we both agreed that the short time the warning light was on; the lack of smoke; smells and assessment of the avionics by the Flight Attendant and myself that the indication was a nuisance warning. At this time we were on the arrival. We agreed that if the warning returned or we could smell or see smoke we would make an emergency landing at the nearest suitable airport. The warning did not return and we continued to our destination without interruption.