The MIL is the only lamp that is controlled directly by
the PCM, all other indicator lamps/guages are controlled by the BCM, or the
IPC. Refer to Body and Accessories to diagnose these items.
MIL Operation
The Malfunction Indicator Lamp (MIL) is located on the instrument panel
(CHECK ENGINE) or (SERVICE ENGINE SOON). The MIL performs the following functions:
| • | It informs the driver that a problem has occurred and that the
vehicle should be taken for service as soon as possible. |
| • | As a bulb check and system check, the MIL will illuminate with
the ignition switch on and the engine not running. when the engine is started,
the MIL will turn off. If the MIL remains on, the self-diagnostic system
has detected a problem. If the problem goes away, the MIL will turn off
in most cases, but a diagnostic trouble code will remain stored. |
| • | If the MIL is illuminated, 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. |
Perform the Powertrain OBD System Check first, when the following conditions
are present:
| • | When the MIL does not turn on when the ignition switch is turned
to the RUN position. |
| • | When the MIL remains on while the engine is running. |
| • | When you suspect a driveability problem. |
