Malfunction Indicator Light (Mil)

WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Lexus SC 430, 2003 Lexus RX 300, 2003 Lexus LX 470, 2003 Lexus LS 430, and 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

Engine Control Module (ECM) is equipped with self-diagnostic system. By analyzing various input signals, ECM detects system malfunctions related to various operating parameters. When malfunction occurs, ECM will inform driver by turning on Malfunction Indicator Light (MIL) on instrument panel. If self-diagnostic system detects a fault, it stores a trouble code in ECM memory and grounds MIL circuit, which causes MIL to come on. For more information, see appropriate SELF-DIAGNOSTICS article.

Diagnostic Trouble Codes (DTC) may be set by malfunction of various engine sensors, switches or circuits. DTC is stored in ECM memory. When DTC is stored, MIL on instrument panel will come on. DTC can be retrieved for system diagnosis. For additional information on self-diagnostic system, see appropriate SELF-DIAGNOSTICS article.