Malfunction Indicator Lamp: Description and Operation

MALFUNCTION INDICATOR LAMP
The malfunction indicator lamp (MIL) is located in the instrument panel cluster. The MIL will display as either "SERVICE ENGINE SOON" or one of the following symbols when commanded ON:









POWERTRAIN CONTROL MODULE
The powertrain has electronic controls to reduce exhaust emissions while maintaining excellent driveability and fuel economy. The powertrain control module (PCM) is the control center of this system. The PCM monitors numerous engine and vehicle functions. The PCM constantly looks at the information from various sensors and other inputs, and controls the systems that affect vehicle performance and emissions. The PCM also performs the diagnostic tests on various parts of the system. The PCM can recognize operational problems and alert the driver via the malfunction indicator lamp (MIL). When the PCM detects a malfunction, the PCM stores a diagnostic trouble code (DTC). The problem area is identified by the particular DTC that is set. The control module supplies a buffered voltage to various sensors and switches. Review the components and wiring diagrams in order to determine which systems are controlled by the PCM.

SERVICE VEHICLE SOON
The instrument panel cluster (IPC) illuminates the service vehicle soon indicator during any of the following conditions:
* The body control module (BCM) detects a PASSLOCK failure. The BCM sends a class 2 message to the IPC requesting illumination.
* The BCM detects a malfunction in the passive trunk release system. The BCM sends a class 2 message to the IPC requesting illumination.
* The BCM detects a failure in the traction control system. The BCM sends a class 2 message to the IPC requesting illumination.
* The IPC detects a mismatch between its part number and the vehicle platform configuration sent by the BCM via a class 2 message.