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 cruise control module
- The clutch start switch, if equipped with a manual transmission
- The On/Off switch
- The powertrain control module (PCM)
- The Resume/Accel. Switch
- The Set/Coast Switch
- The stop lamp switch
- The torque converter clutch (TCC) brake switch
- 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
- R/A
- 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 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 cruise control On/Off switch is in the On position, the cruise control module detects a high signal voltage on the cruise on switch signal circuit. When the Set/coast button is pressed, the cruise control module detects a high signal voltage on the set/coast signal circuit. In order to engage the cruise control system, the On/Off switch must be On and the Set button momentarily pressed. The cruise control module will record the selected vehicle speed. When the R/A switch is pressed, the cruise control module detects a high signal voltage on the resume/accel switch signal circuit. Momentarily pressing the R/A switch will recall the previous selected vehicle speed that is recorded in the cruise control module, when the cruise control system has been disengaged by depressing the brake pedal or the clutch pedal. Pressing and holding the R/A switch when the cruise control system is active will allow the vehicle to accelerate to a vehicle speed greater than the current set vehicle speed. When the R/A switch is released, the vehicle speed will decrease to the current set vehicle speed. Pressing and holding the Set/coast switch when the cruise control is active will allow the vehicle speed to decrease from the current set without deactivating the cruise control system. When the Set/coast switch is released, the vehicle will accelerate to the current set vehicle speed.

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 clutch start switch
- The stop lamp switch
- The TCC brake switch

The stop lamp switch, the TCC brake switch, and the clutch start switch are used to disengage the cruise control. The stop lamp switch and the TCC brake switch are incorporated into an assembly and are mounted to the brake pedal bracket. When the cruise control is engaged and the brake pedal is depressed, the normally closed TCC brake switch opens and the normally open stop lamp switch closes. The cruise control module detects a low signal voltage on the TCC brake/cruise control release signal circuit and a high voltage signal on the center high mounted stop lamp (CHMSL) supply voltage/stop lamp supply voltage circuit. When the clutch pedal is depressed, the normally closed clutch start switch opens and the cruise control module detects a low voltage signal on the CPP switch signal circuit. When the cruise control On/Off switch is switched to Off, the cruise control module detects a low voltage signal on the cruise control on 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 to Off, or the ignition switch is turned off.

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.