Start by checking 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's pins.
The cost to diagnose the B1009 GMC code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
EEPROM checksum error detection is internal. No external circuits are involved. For DTC to set, the microprocessor must run the program to detect a checksum error after each power up. The only requirements are voltage and ground. The program runs even if the voltage is out of operating range.
Microprocessor retains an inverse copy of digital value stored in certain blocks of memory in EEPROM. The microprocessor then reads information from those blocks and adds stored inverse value to current value. If they do not equal 0, the microprocessor sets DTC B1009.
When DTC is set, microprocessor reverts to base operation values programmed for those blocks of data that have failed checksum test. Blocks of data that have not failed the checksum test are not affected. DTC clears when microprocessor runs a successful checksum test of EEPROM.
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