Two-Trip Detection Logic
WARNING: This page is about a different car, the 1995 Lexus LS 400. However, it is still accessible from the selected car via links, so may be relevant.
When a malfunction initially occurs, trouble code will be temporarily stored in ECM memory, but MIL on instrument panel will not illuminate. The second time malfunction is detected, MIL on instrument panel will illuminate, provided ignition is turned off and then back on after first malfunction was detected. This is referred to as the 2-Trip Detection Logic and only applies to specified trouble codes. See TROUBLE CODE IDENTIFICATION table.
NOTE:
When road testing vehicle in Check Mode, the Two Trip Detection Logic will not function. Also, MIL will illuminate the first time a malfunction is detected.