Monitoring Procedure

The intent of the "keep alive" memory error diagnostic is to diagnose malfunctions in the ECM by monitoring the checksum. The diagnostic can be simply defined as; the stored checksum does not equal the calculated checksum. This diagnostic operates on a single trip logic

There are two central processor units (CPU) within the ECM which are in constant communication with each other. A series of tokens and acknowledgments are sent out at regular intervals. Should this process be incomplete the communication DTC is flagged on a twin trip logic.