Disconnect the connector (A) from the 3rd clutch transmission fluid pressure switch (B), then remove the 3rd clutch transmission fluid pressure switch.
Install a new 3rd clutch transmission fluid pressure switch with a new sealing washer (C), and tighten the 3rd clutch transmission fluid pressure switch to the specified torque by turning the metal part, not the plastic part.
Check the connector for rust, dirt, or oil, and clean or repair if necessary, then connect the connector securely.