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), and store a 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 DTC will be stored when the ECM detects a corrupted serial peripheral interface (SPI) communication between the main central processing unit (CPU) and the output driver I/C.
• | The ignition switch is turned to ON. |
• | Battery voltage is greater than 11 volts. |
• | The MIL will illuminate. |
• | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers. |
• | A history DTC is stored. |
• | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
• | DTCs can be cleared by using the scan tool. |
• | Disconnect the ECM battery feed for more than 10 seconds. |
Step | Action | Yes | No |
---|---|---|---|
1 | Perform an On-Board Diagnostic System Check. Was the check performed? | Go to Step 2 | |
2 |
Did you complete the replacement? | Go to Step 3 | -- |
3 |
Does the scan tool indicate that this diagnostic has run and passed? | Go to Step 4 | Go to Step 2 |
4 | Are any DTCs displayed that have not been diagnosed? | Go to applicable DTC table | System OK |