As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PIC WAS PERFORMING A PREFLIGHT AND UPON TESTING THE LANDING GEAR HANDLE, DISCOVERED THAT BOTH OF THE RED "GEAR UNSAFE" LAMPS DID NOT ILLUMINATE. THE ACFT WAS THEN GROUNDED AND MX BEGIN TROUBLESHOOTING THE DISCREPANCY. DISCOVERED A DEFECTIVE DIODE CR214 ON THE LANDING GEAR CONTOL HANDLE ASSY. REPLACED DIODE CR214 IAW WIRING MANUAL 32-30-06; OPS CHECK WAS GOOD. ACFT WAS THEN RETURNED TO SERVICE.