B1004
CIRCUIT DESCRIPTIONThe microprocessor uses no external circuits for the operation that sets this DTC. The calculations that determine if this DTC is set are all internal to the processor.
CONDITIONS FOR RUNNING THE DTC
The module microprocessor must be active/awake.
CONDITIONS FOR SETTING THE DTC
The microprocessor calculates a check sum on those areas of memory that hold critical operation data. This is done at a regular interval and is called the periodic check sum. The microprocessor also calculates a check sum on these memory locations when ever new data is written to them. This is called the running check sum. The microprocessor compares the periodic check sum to the running check sum. If they do not match, the microprocessor sets the DTC.
ACTION TAKEN WHEN THE DTC SETS
The microprocessor reverts back to the base programmed critical operating data until new data is learned and stored in KAM.
CONDITIONS FOR CLEARING THE DTC
The DTC will clear when the microprocessor calculates a successful comparison of the periodic check sum to the running check sum.
DIAGNOSTIC AIDS
^ This DTC may be stored as a history DTC with out affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
^ This DTC will never set as current during testing unless there is a non-recoverable memory failure.
^ Intermittent interruptions to either the battery positive voltage or the ground circuits could cause the module to set this DTC.
^ If this DTC is retrieved as both a current and history DTC, replace the module.
TEST
