As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOI - ON APPROACH AND AFTER GEAR EXTENSION, THE LEFT MAIN DOOR AMBER LIGHT REMAINED ILLUMINATED. THE APPROACH WAS ABORTED AND THE ALTERNATE GEAR EXTENSION WAS USED. AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED THE AIRCRAFT AND REPLACED THE MAIN GEAR DOWN SAFE SWITCH AND RESET THE MAIN GEAR DOOR ALTERNATE EXTENSION CABLE. THE OPERATIONAL CHECK WAS GOOD AND THE AIRCRAFT WAS RETURNED TO SERVICE.