Code No. C1803 ACC mode off disagreement; Code No. C1804 ACC deactivation disagreement: Operation
WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.
The ASC-ECU receives ACC control status signal from the ACC/FCM-ECU, and vehicle control status signal from the engine control module via CAN bus lines, respectively.