This is the preferred method for modern drivers. The tuner patches the MED9.1 to listen to the CAN bus packet generated by the "Cruise Control Resume/Set" lever.
Symptom: The ECU throws a "Checksum error - Memory corrupted" even though the car runs. Cause: The patch failed to update the internal RSA signature or CS0/CS1 checksums. Fix: Use a debugger (like Trace32) to watch the checksum routine or switch to a "noCrc" modified binary (not recommended for daily drivers). med9.1 multimap