What was found
FLIGHT 4331, CREW REPORTED ON TAKE OFF, RECEIVED A "LANDING GEAR AIR/GND FAIL MESSAGE ON EICAS. LANDING GEAR WAS IN LOCKED DOWN POSITION. CREW RAN CHECKLIST PER AOM VOL 1, DURING WHICH TIME THE MESSAGE EXTINGUISHED ON ITS OWN AND WERE ABLE TO RETRACT THE GEAR NORMALLY. DECLARED AN EMERGENCY. RETURNED AND LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REMOVED AND REPLACED NOSE WHEEL WEIGHT ON WHEELS SENSOR HARNESS. OPS CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.