Circuit Description

Module calibrations are stored in the EEPROM. When ignition is first turned on, module performs internal tests on EEPROM and can determine the integrity of its non-volatile memory. Module compares previously used checksum with checksum calculated when ignition is first turned on. If checksums do not match, module will indicate a calibration malfunction (checksum error) is current.

DTC will set when stored checksum does not match the calculated checksum. DTC will also set when module detects an internal memory malfunction (checksum error), and when these conditions occur when ignition is first turned on.