As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) WHEN THE GEAR WAS SELECTED DOWN ON APPROACH, THE LEFT MAIN GEAR GREEN LIGHT DID NOT COME ON AND THE CREW CARRIED OUT A MISSED APPROACH. AFTER THE CREW CYCLED THE GEAR THE LIGHT DID COME ON AND THEY CARRIED OUT AN UNEVENTFUL LANDING. MAINTENANCE TRACED THE PROBLEM TO A FAILED LEFT DOWNLOCK SWITCH.