Circuit Description

The module calibrations are stored in the EEPROM. When ignition is first turned on, module performs internal tests on the EEPROM and can determine the integrity of its non-volatile memory.

Module compares its previously stored checksum with checksum calculated when ignition is first turned on. If the 2 checksums do not match, module will indicate a calibration malfunction (checksum error), setting DTC.

Conditions for setting DTC:

• Stored checksum does not match calculated checksum.
• Module detects an internal memory malfunction.
• Conditions must occur when ignition is first turned on.