What was found
ON FLT 4604 AT APPROXIMATELY 500 FT ABOVE GROUND LEVEL THE CREW RECEIVED A WEIGHT ON WHEEL INPUT & WEIGHT ON WHEELS OUTPUT MESSAGE AND PROXIMITY SYSTEM CHANNEL EICAS MESSAGE. THE CAPTAIN DECLARED AN EMERGENCY AND ELECTED TO RETURN TO FIELD. ACFT LANDED WITHOUT INCIDENT. CREW PULLED THE CIRCUIT BREAKERS WHEN PARKED. THE ACFT REMOVED FROM SERVICE. REMOVED AND REPLACED PROXIMITY SENSORY ELECTRONIC UNIT IAW AMM 32-61-01. THE OPERATIONAL CHECK WAS GOOD PER 32-61-00. CHECKED NOSE STRUT FOR PROPER NITROGEN SERVICE, SERVICED PER 12-12-32. THE AIRCRAFT WAS RETURNED TO SERVICE.