Dakota 4WD V6-3.9L VIN X (1997)
Malfunction Indicator Lamp: Description and Operation
MALFUNCTION INDICATOR LAMP (MIL)
As a functional test, the MIL (check engine) illuminates at key-on before engine cranking. Whenever the Powertrain Control Module (PCM) sets a
Diagnostic Trouble Code (DTC) that affects vehicle emissions, it illuminates the MIL. If a problem is detected, the PCM sends a message to the
instrument cluster to illuminate the lamp. The PCM illuminates the MIL only for DTC's that affect vehicle emissions. There are some monitors that
may take two consecutive trips, with a detected fault, before the MIL is illuminated. The MIL stays on continuously when the PCM has entered a
Limp-In mode or identified a failed emission component.
Also, the MIL either flashes or illuminates continuously when the PCM detects active engine misfire. Refer to Misfire Monitoring.
Additionally, the PCM may reset (turn off) the MIL when one of the following occur:
-
PCM does not detect the malfunction for 3 consecutive trips (except misfire and Fuel system Monitors).
-
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.
BULB CHECK
Each time the ignition key is turned to the ON position, the malfunction indicator (check engine) lamp on the instrument panel should illuminate for
approximately 2 seconds then go out. This is done for a bulb check.
CIRCUIT OPERATION
The Powertrain Control Module (PCM) provides ground for the MIL on circuit G3. Circuit G3 connects to cavity C17 of the PCM.
