Theory Of Operation
WARNING: This page is about a different car, the 2013 Dodge Avenger and 2013 Chrysler 200. However, it is still accessible from the selected car via links, so may be relevant.
After the controller is reset (ignition on from an off position), the microprocessor checks the integrity of the program memory (ROM). A checksum is calculated by adding all used bytes in the program memory. The sum should be the same as a known constant stored in memory. If the integrity of the program memory fails, the MIL will illuminate after 10 seconds of vehicle operation and transmission will be placed in limp-in.