Durango 4WD V8-5.9L VIN Z (1998)
Malfunction Indicator Lamp: Description and Operation
SYSTEM OPERATION
The Check Engine or Malfunction Indicator Lamp (MIL) gives an indication when the Powertrain Control Module (PCM) has recorded a
Diagnostic Trouble Code (DTC) for an On-Board Diagnostics II (OBDII) emissions-related circuit or component malfunction. The lamp is
controlled by the instrument cluster circuitry based upon messages received from the PCM on the Chrysler Collision Detection (CCD) data bus.
The PCM sends lamp-on messages for about two seconds when the ignition switch is turned to the On position as a bulb test.
Following the bulb test, the PCM uses inputs from many emissions-related circuits and sensors, along with its internal programming, to decide
whether a condition exists that requires the MIL lamp to be turned on. The PCM then sends the proper messages to the instrument cluster on the
CCD data bus to turn the lamp on or off.
