Hard Faults

Hard faults cause Malfunction Indicator Light (MIL) to illuminate and remain on until the malfunction is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined. If using voltmeter, see appropriate diagnostic fault chart. See Figure. If using DRB, see SELF-DIAGNOSTIC TESTS  in this article. If a sensor fails, ECU will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but loss of good driveability may result.