DTC B1004: Keep Alive Memory (KAM): Description

Module uses no external circuits for operation that sets DTC B1004. Calculations that determine if DTC B1004 is set are all internal to processor. DTC B1004 will set while module is active (awake). Module calculates a checksum on areas that hold critical operation data at a regular interval, called periodic checksum. Module also calculates a checksum on these memory locations whenever new data is written to them. Module compares periodic checksum to running checksum. If they do not match, DTC B1004 will set.

When DTC B1004 sets, module reverts back to base programmed critical operating data until new data is learned and stored in KAM. DTC B1004 will clear when module calculates a successful comparison of periodic checksum and running checksum.