Circuit Description

Internal fault detection is handled inside control module. No external circuits are involved.

DTC B1009 sets when, control module detects a checksum error. Control module runs checksum program three times with data stored in EEPROM.

When DTC B1009 sets, the microprocessor sets DTC as current. Microprocessor uses default information for operations that depend on data stored in EEPROM.

A current DTC B1009 will clear when microprocessor makes a successful checksum calculation with the data stored in EEPROM. A history DTC B1009 will clear after 100 consecutive ignition cycles if condition for malfunction is no longer present.