Cirrus V6-2.5L VIN H (1995)
Malfunction Indicator Lamp: Description and Operation
MALFUNCTION INDICATOR LAMP (MIL) - PCM OUTPUT
If a problem is detected, the PCM sends a message over the CCD Bus to the Body Control Module (BCM). The BCM interprets this message and
sends a signal to the instrument cluster to illuminate the malfunction indicator (Check Engine) lamp. The lamp comes on each time the ignition key
is turned ON and stays on for a 3 second bulb test.
The MIL lamp stays on continuously when the PCM has entered a Limp-In mode or identified a failed emission component. During Limp-in
Mode, the PCM attempts to keep the system operational. The malfunction indicator lamp signals the need for immediate service. In limp-in mode,
the PCM compensates for the failure of certain components that send incorrect signals. The PCM substitutes inputs from other sensors for the
incorrect signals.
If the PCM detects active engine misfire sever enough to cause catalyst damage, it flashes the malfunction indicator (Check Engine) lamp. At the
same time the PCM also sets a Diagnostic Trouble Code (DTC).
Signals that can trigger the Malfunction Indicator Lamp (MIL).
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Camshaft Position Sensor
-
Intermittent Cam or Crank Sensor
-
Deteriorated Catalytic Convertor
-
Deteriorated Fuel System
-
Deteriorated EGR System
-
Deteriorated EVAP System
-
Deteriorated Heated Oxygen Sensors
-
Engine Coolant Temperature Sensor
-
Fuel Injectors
-
Fuel Pump Relay
-
Heating Element in Oxygen Sensors
-
Idle Air Control Motor
-
Idle Speed
-
Ignition Coils
-
Intake Air Temperature Sensor
-
Manifold Absolute Pressure Sensor
-
Park/Neutral Switch (Automatic Transmission)
-
PCM Internal Self Test
-
Radiator Fan Relay
-
Throttle Position Sensor
-
Vehicle Speed Sensor
The MIL can also display DTC's. Cycle the ignition switch on, off, on, off, on, within 5 seconds and the PCM displays any DTC's stored in
memory.
CIRCUIT OPERATION
The check engine lamp is used to indicate to the operator of a problem in the engine control system. If a problem is detected, the Powertrain
Control Module (PCM) sends a message over the CCD Bus to the Body Control Module (BCM).
The BCM interprets this message and sends a signal to the instrument cluster to illuminate the lamp. This lamp also is illuminated, for a few
seconds, when the ignition switch is moved from the OFF to the RUN position as a bulb check. The bulb check operation is controlled by the
PCM.
