The engine control module (ECM) is the control center of the fuel injection system. If 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), and store a DTC or DTCs which identify the problem areas to aid the technician in making repairs. An electronically 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 DTC will be stored when the ECM detects corrupted serial peripheral interface (SPI) communication between the main CPU and the output driver I/C.

This diagnostic procedure supports the following DTC:

DTC P1655 Control Module Internal Performance.

The ECM detects a low power counter error for more than 3 seconds