As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED THAT AFTER TAKEOFF THEY RECEIVED A LGL AIR/GND FAIL CAUTION MESSAGE ON EICAS FOLLOWED BY REV 1 (2) DISAGREE. THE CREW FOLLOWED AOM, VOL1 CHECKLIST AND DECLARED AN EMERGENCY. THE ACFT LANDED WITHOUT INCIDENT. THE MESSAGE STAYED ON UNTIL AFTER LANDING THEN ALL CLEARED. THE ACFT WAS REMOVED FROM SERVICE. R & R THE LANDING GEAR ELECTROINC UNIT IAW AMM 32-32-01. THE OPS CHECK WAS GOOD. THE ACFT WAS RETURNED TO SERVICE.