What was found
ON FLIGHT 9808 AFTER TAKEOFF THE CREW REPORTED THE LANDING GEAR WOULD NOT RETRACT. THE CREW RECEIVED A LANDING AIR/GROUND FAIL MESSAGE ON EICAS. THE CREW ELECTED TO RETURN TO CMH AND LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED THE NOSE LANDING GEAR PROXIMITY SWITCH. THE OPERATIONAL CHECK WAS GOOD, REFERENCE EMB AMM 32-63-02. ALSO REMOVED AND REPLACED THE NOSE LANDING GEAR HARNESS, REFERENCE AMM 32-00-03. EXTENSION AND RETRACTION OF LOG SYSTEM REFERENCE EMB AMM 32-30-00. THE HARNESS PART AND SERIAL NUMBERS: P/N 14521495403, S/N NA. THE AIRCRAFT WAS RETURNED TO SERVICE.