Circuit Description

The Engine Control Module (ECM) is the control center of the fuel injection system. It constantly looks at the information from various sensors and controls the systems that affect vehicle performance. The ECM also performs the diagnostic function of the system. It can recognize operational problems, alert the driver through the Malfunction Indicator Lamp (MIL) (Check Engine) and store a Diagnostic Trouble Code (DTC) or DTCs which identify the problem areas to aid the technician in making repairs. An Electrically Erasable Programmable Read Only Memory (EEPROM) is used to house the program information and the calibrations required for engine, transmission and powertrain diagnostics operation. The ECM checks operation of Lower Power Counter Integrated Chip (I/C) and communication between main CPU and Lower Power Counter I/C. The ECM monitors EEPROM reset flag and Lower Power Counter I/C overflow bits. If the ECM detects if Lower Power Counter I/C has been reset due to battery disconnector Lower Power Counter I/C malfunction, the Diagnostic Trouble Code (DTC) will stored.