B1009
CIRCUIT DESCRIPTIONThe EEPROM check sum error detection is handled inside the control module. No external circuits are involved.
CONDITIONS FOR RUNNING THE DTC
The microprocessor runs the program to detect a check sum error after each "power up". The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.
CONDITIONS FOR SETTING THE DTC
The microprocessor retains an inverse copy of the digital value stored in certain blocks of memory in the EEPROM. The microprocessor then reads the information from those certain blocks and adds the stored inverse value to the current value. If they do not equal 0, the microprocessor sets this DTC.
ACTION TAKEN WHEN THE DTC SETS
The microprocessor reverts to base operation values programed for those blocks of data that have tailed the check sum test. The blocks of data that have not failed the check sum test are not affected.
CONDITIONS FOR CLEARING THE DTC
^ A current DTC clears when the malfunction is no longer present.
^ A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
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.
^ If this DTC is retrieved as both a current and history DTC, replace the module.
TEST
