Hard Failures
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 2000 GMC Savana Special, 2000 GMC Savana Camper Special, 2000 GMC Savana, 2000 GMC Pickup, and 2000 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
Most hard failures cause MIL to illuminate and remain illuminated until malfunction is repaired. If MIL illuminates and remains illuminated (light may flash) during vehicle operation, cause of malfunction must be determined. See DIAGNOSTIC PROCEDURE . If a sensor fails, PCM will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but will most likely display degraded driveability.