MIL Function

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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 ECM.