The cruise control system is of the electronic stepper type and consists of an Electronic Control Unit (ECU), actuator, control switch and various other switches such as the parking brake switch. The ECU, when signaled by the steering column mounted switch, will command the electronic stepper motor to activate. This will lock the throttle, via a cable, thus holding the speed of the vehicle to the drivers desired setting.
Toyota's cruise control system also has its own diagnostic circuit that monitors and checks for malfunctions. If a malfunction occurs during cruise control driving, the ECU will cancel cruise control, and will blink the cruise control indicator to alert the driver of a problem in the system. At the same time the malfunction is stored in the ECU's memory as a diagnostic trouble code.