As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 3559 - PHL, LANDING GEAR INOP AND CAUTION LIGHT CAME ON DURING CRUISE FLIGHT. CREW DIVERTED INTO PHL. MAINTENANCE TROUBLESHOT SYSTEM, PERFORMED SEVERAL RETRACTION TESTS AND COULD NOT DUPLICATE PROBLEM. REMOVED AND REPLACED PSEU FOR TROUBLESHOOTING.