This Diagnostic Trouble Code (DTC) may be stored as history without affecting the operation of the module. If DTC is stored only as history and not current, do not replace the module. DTC will never set as current during testing unless a non-recoverable memory failure. Intermittent interruptions to either hot at all times supply or processor ground will cause the module to set DTC. If this DTC is retrieved as both current and history, replace the module that set DTC.
Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
The cost to diagnose the B1004 Chevrolet code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.
This fault is internal. No external circuits are involved. Module microprocessor must be active/awake for the Diagnostic Trouble Code (DTC) to set. The microprocessor calculates the checksum on those areas of memory that hold critical operation data. This is done at a regular interval and is called a periodic checksum. The microprocessor also calculates a checksum on these memory locations whenever new data is written to them. This is called the running checksum. The microprocessor compares periodic checksum to running checksum. If they do not match, the microprocessor sets DTC B1004.
When DTC is set, microprocessor reverts back to base programmed critical operating data until new data is learned and stored in Keep Alive Memory (KAM). DTC will clear when the microprocessor calculates a successful comparison of periodic checksum to running checksum.
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