T100 SR5 Extra Cab Pickup 4WD V6-3.4L (5VZ-FE) (1998)
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Malfunction Indicator Lamp: Description and Operation
OBD II regulations require that the vehicle's on-board computer lights up the Malfunction Indicator Lamp (MIL) on the instrument panel when
the computer detects a malfunction in the computer itself or in drive system components which affect vehicle emissions. In addition to the MIL
lighting up when a malfunction is detected, the applicable Diagnostic Trouble Code (DTC) prescribed by SAE J2012 are recorded in the ECM
memory.
If the malfunction has been repaired, the MIL goes off automatically but the DTCs remain recorded in the ECM memory.
