As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) THE FLIGHT CREW REPORTED THE L/H RED "GEAR UNSAFE" LIGHT ILLUMINATED ACCOMPANIED BY GEAR HORN, STICK SHAKER, AND MANUAL SPOILER FAULT WHILE AT THE GATE AFTER SWITCHING FROM GROUND POWER TO APU. MAINTENANCE INVESTIGATION REVEALED AN OPEN CIRCUIT IN THE L/H MAIN GEAR SIDESTAY PROXIMITY SENSOR. THE SIDESTAY ASSEMBLY WAS REPLACED AND THE AIRCRAFT WAS RETURNED TO SERVICE.