Toyota and Lexus 89663-35731 Firmware
A catalog reference for Toyota and Lexus firmware identifier 89663-35731 and its ECU calibration part-number family.
89663-35731 is a Toyota-format calibration identifier in the 89663 part-number family, commonly associated with engine control module software. That association is tentative for this specific file: the identifier alone does not establish its vehicle application or the exact system behavior controlled by this calibration.
What the calibration family does
An engine control module uses software and calibration data to manage functions such as fuel delivery, ignition timing and emissions control. These functions affect how an engine starts, responds to the accelerator and operates under changing conditions. The 89663-35731 catalog entry does not identify which of those behaviors, if any, differs in this particular revision.
The related catalog name is 89663-35731. It does not specify a vehicle model, controller designation or stock or modified variant label, so it cannot establish fitment or a special feature.