INSPECTION PROCEDURE 9: Sometimes The Rain Sensitive AUTO Wiper Function Works Even Though There Is No Rainfall <Vehicles With Lighting Control Sensor>: Notes
WARNING: This page is about a different car, the 2012 Mitsubishi Lancer. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
Whenever ECU is replaced, ensure that the input and output signal circuits are normal.