Powertrain Control Module (PCM) Description: Notes

The powertrain control module (PCM) interacts with many emission related components and systems, and monitors emission related components and systems for deterioration. OBD II diagnostics monitor the system performance and a diagnostic trouble code (DTC) sets if the system performance degrades.

The malfunction indicator lamp (MIL) operation and the DTC storage are dictated by the DTC type. A DTC is ranked as a Type A or Type B if the DTC is emissions related. Type C is a non-emissions related DTC.

The PCM is in the engine compartment. The PCM is the control center of the engine controls system. The PCM controls the following components:

• The fuel injection system
• The ignition system
• The emission control systems
• The on-board diagnostics
• The A/C and fan systems

The PCM constantly monitors the information from various sensors and other inputs, and controls the systems that affect the vehicle performance and the emissions. The PCM also performs diagnostic tests on various parts of the system. The PCM can recognize operational problems and alert the driver via the MIL. When the PCM detects a malfunction, it stores a DTC. The condition is identified by the particular DTC that is set. This aids the technician in making repairs.