Circuit/System Description

A security policy value called Not Before ID is stored in K56 Serial Data Gateway Module memory. This is a hex number identifier used by cyber security calibrations to prevent programming an earlier model year security calibration into a current or subsequent model year. If the K56 Serial Data Gateway Module is reprogrammed with a security calibration that contains a security policy value greater than the value that is currently stored in memory, then the security policy value is updated in memory to the new value. The value in memory can only be incremented and can never be decremented. If the K56 Serial Data Gateway Module is reprogrammed with a security calibration that contains a security policy value lower than the value stored in the memory, then DTC U1980 will be set.