Malfunction Indicator Lamp (MIL) Inoperative
CIRCUIT DESCRIPTIONThere should be a steady malfunction indicator lamp (MIL) with the ignition ON and the engine OFF. Ignition feed voltage is supplied directly to the MIL. The powertrain control module (PCM) turns the MIL ON by grounding the MIL control circuit. No MIL with the key ON, engine not running suggests an open in the battery positive and ignition positive voltage feed fuses and circuits.
MIL OPERATION
MIL is located on the instrument panel and is displayed as CHECK ENGINE lamp.
MIL FUNCTION
^ The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible.
^ The MIL illuminates during a bulb test and a system test.
^ A DTC will be stored if a MIL is requested by the diagnostic.
MIL ILLUMINATION
^ The MIL will illuminate with ignition ON and the engine not running.
^ The MIL will turn OFF when the engine is started.
^ The MIL will remain ON if the self-diagnostic system has detected a malfunction.
^ The MIL may turn OFF if the malfunction is not present.
^ If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated so long as the ignition switch is ON.
^ 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 SYSTEM CHECK
Perform the Computers and Controls Systems Diagnostic System Check, when the following conditions are present:
^ When the MIL does not turn ON when the ignition switch is turned to the RUN position. See above for MIL operation.
^ When the MIL remains ON while the engine is running
^ When the MIL is flashing while the engine is running
^ When a driveability symptom is determined Initial Inspection and Diagnostic Overview
DIAGNOSTIC AIDS
Inspect for the following conditions:
^ If the engine runs OK, inspect for a malfunctioning MIL, an open in the MIL control circuit, or an open in the instrument cluster (IC) ignition feed.
^ If the engine cranks but will not run, inspect for an open PCM ignition or battery feed or a faulty PCM to engine ground.
^ PCM and engine grounds for clean and secure connections
TEST
