As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB OPS THE AFT AIR-STAIR GREEN LIGHT ILLUMINATED. ACFT RETURNED, WHERE IT LANDED WITH OUT INCIDENT. POST FLIGHT INSP WAS PERFORMED, THE TREAD LIGHT SWITCH WAS DETERMINED TO BE AT FAULT. ITEM WAS DEFERRED AND ACFT WAS RETURNED TO SERVICE. NO OTHER DEFECTS WERE NOTED.