C 1500 Yukon 2WD V8-5.3L VIN T (2002)
Malfunction Indicator Lamp: Testing and Inspection
Malfunction Indicator Lamp (MIL) Inoperative
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. There should be a steady MIL with the ignition ON and the engine OFF.
MIL OPERATION
The MIL is located on the instrument panel (IP).
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 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 problem is intermittent, refer to Intermittent Conditions. See: Powertrain Management/Computers and Control Systems/Testing and
Inspection/Initial Inspection and Diagnostic Overview/Intermittent Conditions
TEST DESCRIPTION
