Dakota R/T 2WD 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.
Additionally, the PCM may reset (turn off) the MIL when one of the following occur:
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PCM does not detect the malfunction for 3 consecutive trips (except misfire and Fuel system Monitors).
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PCM does not detect a malfunction while performing three successive engine misfire or fuel system tests. The PCM performs these tests while
the engine is operating within +/- 375 RPM of and within 10% of the load of the operating condition at which the malfunction was first
detected.
