Engine Control Module (ECM)
WARNING: This page is about a different car, the 2000 Cadillac Catera. However, it is still accessible from the selected car via links, so may be relevant.
All cruise control functions are monitored and controlled by the Engine Control Module (ECM). When the ECM receives an input from the cruise control functional switches, a control signal to throttle motor is sent to modify the throttle angle to maintain desired cruise speed.