Cruise Control: Description and Operation

Cruise Control

How the Circuit Works

This vehicle does not use a throttle cable or cruise control actuator to maintain the vehicle speed during the cruise control mode. A throttle actuator control motor, located on the side of the throttle housing, is used to open and close the throttle plate for routine driving and cruise conditions.

Power Supply
Battery voltage is supplied at all times through fuse 1 (in the under-dash fuse/relay box) to the throttle actuator control module relay contacts, through fuse 7 (in the under-hood fuse/relay box) to the relay control module, and through fuse 13 (in the under-hood fuse/relay box) to the horn relay coil and brake pedal position switch. Battery voltage is also supplied at all times through fuse 7 (in the under-dash fuse/relay box) to the gauge control module and then to the main switch of the cruise control combination switch.

With the ignition ON (II) or START (III), battery voltage is supplied through fuse 18 (in the under-dash fuse/relay box) to the brake pedal position switch and then to the ECM/PCM.

System Description
When the main switch is pressed, a battery voltage input is removed from the gauge control module and the cruise control main switch indicator LED illuminates. With the shift lever in D or L (A/T) or with the clutch pedal not pressed (M/T), a path to ground is provided for the drive input ("A") or switch input (M/T) to the ECM/PCM. The ECM/PCM detects that the shift lever is in D or L (A/T) or the clutch pedal is not pressed (M/T) through this input, which enables the cruise control.

When the Set switch is pressed, a voltage signal is sent to the gauge control module. The gauge control module grounds the cruise control indicator LED, illuminating it. The gauge control module communicates the set signal via multiplex communication lines to the ECM/PCM. Using the vehicle speed input obtained from the output shaft (countershaft) speed sensor, the ECM/PCM communicates the cruise control information to the throttle actuator control module. The throttle actuator control module sends signals to, and receives signals from, the TP sensor/throttle actuator, which opens and closes the throttle to maintain the set speed.

When the brake pedal is pressed, a battery voltage input is sent to the ECM/PCM through fuse 13 (in the under-hood fuse/relay box) and the battery voltage input through fuse 18 (in the under-dash fuse/relay box) is removed. The ECM/PCM communicates the brake pedal pressed information via multiplex communication lines to the gauge control module, which removes ground from the cruise control indicator LED, turning it off. The information is also communicated to the throttle actuator control module, which removes the cruise control system's control of the throttle.

When the Resume switch is pressed, a voltage signal is sent to the gauge control module. The gauge control module grounds the cruise control indicator LED, illuminating it. The gauge control module communicates the resume signal via multiplex communication lines to the ECM/PCM.

Using the vehicle speed input obtained from the output shaft (countershaft) speed sensor, the ECM/PCM communicates the cruise control information to the throttle actuator control module. The throttle actuator control module sends signals to, and receives signals from, the TP sensor/throttle actuator, which opens and closes the throttle to resume and maintain the previously set speed.

When the Cancel switch is pressed, two voltage signals are sent to the gauge control module. The gauge control module removes ground from the cruise control indicator LED, turning it off. The gauge control module communicates the cancel signal via multiplex communication lines to the ECM/PCM. The information is also communicated to the throttle actuator control module, which removes the cruise control system's control of the throttle.