As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
A TECHNICIAN REMOVED THE INSTRUMENT PANEL GRADUATOR, LIGHT (LIGHTING DIMMER) FOR ACCESS PURPOSES. IT WAS FOUND UPON REMOVAL THAT THE 24 PIN ELECTRICAL CONNECTOR ON THIS DIMMER HAD MODERATE CORROSION ON OVER HALF OF THE CONNECTOR PINS WITH SIGNS OF CORROSION ON THE PC BOARD. THE SOURCE OF THE CORROSION IS BELIEVED TO BE WATER INGRESS FROM THE FRESH AIR DUCT LOCATED ABOVE THIS PART.