As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, ALL THREE LANDING GEAR UNSAFE LIGHTS REMAINED ILLUMINATED AFTER LANDING GEAR RETRACTION. THE FLIGHT CREW RECYCLED THE LANDING GEAR WITH UNSAFE LIGHTS REMAINING ILLUMINATED. LANDING GEAR UNSAFE LIGHTS EXTINGUISHED DURING FLIGHT DESCENT. AIRCRAFT LANDED AT DTW WITHOUT INCIDENT. MAINTENANCE REPLACED THE LANDING GEAR PROXIMITY SWITCH ELECTRONICS UNIT. OPERATIONAL CHECK NORMAL.