As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON GEAR EXTENSION GOT ALL THREE GREEN GEAR DOWN LIGHTS. AT 200 AGL THE GPWS 'GEAR UNSAFE MODE' SOUNDED AND THREE RED UNSAFE LIGHTS ILLUMINATED. MISSED APPROACH AND VISUALLY CHECKED GEAR DOWN. NO GPWS SOUNDED ON THE RUNWAY. REPLACED LANDING GEAR ACCESS UNIT AND GPWS COMPUTER. CHECKED PER M/M 32-09-00, LANDING GEAR WARNING CHECKS OK.