DTC C1340: Stoplight Switch: Notes
WARNING: This page is about a different car, the 2009 Mitsubishi Eclipse. However, it is still accessible from the selected car via links, so may be relevant.
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
CAUTION:
If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.