Engine Control Module
WARNING: This page is about a different car, the 2000 Lexus SC 400, 2000 Lexus SC 300, 2000 Lexus LS 400, 2000 Lexus GS 400, and 2000 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
Cruise control function has been integrated with the Engine Control Module (ECM). ECM controls throttle control motor based on various inputs. If a system fault occurs, ECM will store a Diagnostic Trouble Code (DTC) that can be retrieved to aid in diagnosis.