Express 2500 V8-4.8L (2007)
Malfunction Indicator Lamp: Testing and Inspection
Malfunction Indicator Lamp (MIL) Always On
Malfunction Indicator Lamp (MIL) Always On
Circuit Description
Battery positive voltage is supplied directly to the malfunction indicator lamp (MIL). The powertrain control module (PCM) turns the MIL ON by
grounding the MIL control circuit.
MIL Operation
The MIL is located on the instrument panel cluster (IPC).
MIL Function
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The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible.
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The MIL illuminates during a bulb test and a system test.
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A DTC will be stored if a MIL is requested by the diagnostic.
MIL Illumination
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The MIL will illuminate with the ignition switch ON and the engine not running.
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The MIL will turn OFF when the engine is started.
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The MIL will remain ON if the self-diagnostic system has detected a malfunction.
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The MIL may turn OFF if the malfunction is not present.
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If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated so long as the ignition switch is ON.
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If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON.
Diagnostic Aids
If the condition is intermittent, Refer to Testing for Intermittent Conditions and Poor Connections in Diagnostic Aids. See: Testing and
Inspection/Component Tests and General Diagnostics
Test Description
Step 1 - Step 6
The number below refers to the step number on the diagnostic table.
2. This step determines if the condition is with the MIL control circuit or the PCM.
