Cruise Control: Description and Operation

CRUISE CONTROL DESCRIPTION AND OPERATION

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at vehicle speeds above 40 km/h (25 mph). Steep grades may cause variations in the selected vehicle speeds.

The following are the main components of the cruise control system:
- The powertrain control module (PCM)
- The On/Off switch
- The Resume/Accel. Switch
- The Set/Coast Switch
- The stop lamp switch
- The torque converter clutch (TCC) brake switch
- The cruise control module
- The clutch pedal position (CCP) switch, if equipped with a manual transmission
- The vehicle speed sensor

Cruise Control Engaged
The cruise control system will engage and adjust vehicle speed based on the activation of the following cruise control switches:
- On/Off
- Resume/Accel.
- Set/Coast

The cruise control switches are located on the multifunction/turn signal lever.

The cruise control module monitors the signal circuits of the cruise control switches in order to determine when to capture and maintain the selected vehicle speed. The cruise control module receives the vehicle speed signal from the PCM, via the vehicle speed signal circuit. The cruise control module is an electronic controller and an electric stepper motor. The electric controller monitors the vehicle speed and operates the electric stepper motor. The electric stepper motor moves a strap that is attached to the cruise control cable in order to move the throttle linkage.

Ignition positive voltage is supplied from the 10-ampere CRUISE fuse, to the cruise control switch and to the cruise control module via the ignition 3 voltage circuit. When the normally open cruise control On/Off switch is turned On, the switch closes and the cruise control module detects a high signal voltage on the cruise on switch signal circuit. When the normally open Set/Coast switched is pressed, the switch closes and the cruise control module detects a high signal voltage on the set/coast signal circuit. To engage the cruise control system, the On/Off switch must be On and the Set button momentarily pressed. The cruise control module grounds the cruise control engaged signal circuit to the PCM. The PCM will confirm that the cruise control enable criteria has been met. The cruise control module will record the selected vehicle speed. The PCM sends a class 2 message to the instrument panel cluster in order to illuminate the cruise control indicator. Pressing the accelerator pedal, while the cruise control system is engaged, will allow the driver to override the cruise control system in order to accelerate the vehicle beyond the current set vehicle speed. When the accelerator pedal is released, the vehicle will decelerate and resume the current set vehicle speed. The driver can also override the current set vehicle speed via the Set/Coast switch and the Resume/Accel switch. When the cruise control system is engaged, pressing and holding the Set/Coast switch will allow the vehicle to decelerate from the current set vehicle speed without deactivating the cruise control system. When the Set/Coast switch is released, the cruise control module will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the cruise control system is engaged, momentarily pressing the Set/Coast switch will allow the vehicle to decelerate at 1.6 km/h (1 mph) increments for each time that the Set/Coast is momentarily pressed, with a minimum vehicle speed of 37 km/h (23 mph). When the normally open Resume/Accel switch is activated, the switch closes and the cruise control module detects a high signal voltage on the cruise control resume/accel switch signal circuit. Activating and holding the Resume/Accel switch, when the cruise control system is engaged, will allow the vehicle to accelerate to a greater vehicle speed than the current set vehicle speed. When the Resume/Accel switch is released, the cruise control module will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the cruise control system is engaged, momentarily activating the Resume/Accel switch will allow the vehicle to accelerate at 1.6 km/h (1 mph) increments for each time that the Resume/Accel switch is momentarily activated, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed. Momentarily activating the Resume/Accel switch, after the cruise control system has been disengaged by pressing the brake pedal, will recall the previous set vehicle speed that is recorded in the cruise control module.

Cruise Control Disengaged
The cruise control module disengages the cruise control operation based on the signals from the following switches:
- The On/Off switch
- The CCP switch
- The stop lamp switch
- The TCC brake switch

The stop lamp switch, the TCC brake switch, and the CPP switch are used to disengage the cruise control system. The stop lamp and the TCC brake switch are incorporated into an assembly and are mounted to the brake pedal bracket. When the brake pedal is depressed, the normally open stop lamp switch closes and the normally closed TCC brake switch opens. The cruise control module detects a high signal voltage on the stop lamp switch signal circuit and a low signal voltage on the TCC brake switch/cruise control release signal circuit. Depressing the clutch pedal while the cruise control is engaged will disengaged the cruise control system. When the clutch pedal is depressed, the normally closed CPP switch opens and the cruise control module detects a low signal voltage on the CCP switch signal circuit. The vehicle speed stored in the memory of the cruise control module will be erased when the cruise control On/Off switch is turned Off, or the ignition switch is turned off.

When the cruise control system is disengaged, the PCM sends a class 2 message to the IPC in order to deactivate the cruise control indicator.

Cruise Control Inhibited
The cruise control module assembly contains a low speed limit which will prevent system engagement below a minimum speed of 40 km/h (25 mph).

The cruise control will not engage if the cruise control module detects a low voltage signal on the CHMSL supply voltage/stop lamp supply voltage circuit when the brake pedal is depressed.