DTC B1658: EEPROM Checksum Error: Description
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EEPROM check sum error detection is handled inside control module. No external circuits are involved. Microprocessor retains an inverse copy of the digital value stored in certain blocks of memory in the EEPROM. Microprocessor then reads information from certain blocks and adds stored inverse value to current value. If they do not equal 0, microprocessor will sets DTC B1658.
When DTC is set, microprocessor reverts to base operation values programed for those blocks of data. Blocks of data that did not fail check sum test are not affected.
DTC will clear when microprocessor runs a successful check sum test of EEPROM.