As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER SELECTING LANDING GEAR DOWN FOR LANDING, WE RECEIVED 3 GEAR UNSAFE (RED LIGHTS) FOR OVER A MINUTE (APPROX). GEAR THEN CAME DOWN (3 GREEN LIGHTS) WITH NO FURTHER INPUT. REMOVED FROM SERVICE. PERFORMED GVI OF MLG AND NLG, NO DAMAGE NOTED. VERIFIED MAIN AND ALTERNATE INDICATIONS SHOW GEAR DOWN AND LOCKED. FERRIED FLIGHT. R&R OF LANDING GEAR SELECTOR VALVE IAW Q400 AMM TASK 32-31-06-000/400-801. AIRCRAFT RETURNED TO SERVICE.