What was found
LANDING GEAR EXTENSION INDICATIONS (ALL THREE) WENT FROM UP TO DOWN WITH NO TRANSITION, LANDING GEAR LEVER DISAGREE WARNING MESSAGE ALERTED THEN CLEARED WITH THREE GREEN LIGHTS, FLYBY PERFORMED FOR EXTENSION. PERFORMED OPERATIONS CHECKS OF THE EXTENSION AND RETRACTIONS WITH NO DEFECTS IAW EMB AMM 32-32-00. PERFORMED OPERATIONAL CHECK OF LANDING GEAR CONTROL LEVER IAW EMB AMM 32-32-01 WITH NO DEFECTS. REMOVED AND REPLACED LANDING GEAR ELECTRONIC CONTROL UNIT AS PRECAUTIONARY IAW EMB AMM 32-32-01. PERFORMED GEAR RETRACTION AND EXTENSION CHECKS WITH NO DEFECTS, RETURNED AIRCRAFT TO SERVICE.