As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER BEING CLEARED FOR TAKEOFF AND WHILE TAXIING IN FOR RUNWAY 24L, THE F/O WAS PERFORMING THE "BEFORE TAKEOFF" CHECKLIST. AT THE ITEM "WINDSHIELD & PITOT HEAT", A SPARK WAS NOTICED NEAR THE ELECTRICAL CONNECTIONS OF THE LEFT WINDSHIELD.