Cruise Control: Description and Operation: Overview

Speed Control

Speed Control
The speed control system is integrated with the engine management system and uses fueling intervention to automatically maintain a set vehicle speed. Once engaged, the system can also be used to accelerate the vehicle without using the accelerator pedal. The speed control system comprises the following components:
- On/Off/Suspend switch
- '+' and '-' (set/accelerate and decelerate) steering wheel switches
- Resume switch
- Clock spring
- Speed control warning lamp.
The speed control system also uses inputs from the brake pedal switch, the APP (accelerator pedal position) sensor, the ECM (engine control module) and the ABS (anti-lock brake system) control module.
The speed control is operated by the driver using only the steering wheel switches. When speed is active, the ECM (engine control module) regulates the PWM signals to the fuel injectors to adjust the fuel supply as required to maintain the set speed.
During speed control operation, the ECM (engine control module) controls vehicle speed by adjusting fuel injection duration and timing. When the accelerator pedal is pressed with speed control active, the ECM (engine control module) outputs a calculated throttle angle signal in place of the actual throttle angle signals produced by the APP (accelerator pedal position) sensor. The calculated throttle angle is derived from fuel demand.