As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) MASTER SWITCH TURNS ON BY ITSELF USUALLY AT NIGHT AND HIGH MOISTURE. SITUATION CAUSING DEAD BATTERIES. THIS HAS BEEN RECURRING ON SEVERAL DIFFERENT A/C OVER THE PAST 8 YEARS. SUBMITTER STATED COMPANY POLICY IS TO REPLACE WITH A NEW SWITCH EACH TIME, BUT THIS HAS NOT SOLVED THE PROBLEM.