As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RECEIVED A "GEAR DISAGREE" WARNING DURING CLIMB EN ROUTE DTW-SBN, CREW DECLARED AN EMERGENCY AND RETURNED TO DTW, AIRCRAFT LANDED WITHOUT INCIDENT. REMOVED, CLEANED AND REINSTALLED CONNECTOR ON DOOR SELCTOR VALVE. PERFORMED GEAR SWING WITH NO DISCREPANCIES NOTED.