GM Service Manual Online
For 1990-2009 cars only

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 accelerator pedal
    • The clutch start switch, if equipped with a manual transmission
    • The engine control module (ECM), if equipped with a 2.2 L (L61)
    • The powertrain control module (PCM), if equipped with a 3.5 L (L66)
    • The on/off switch
    • The resume/accel switch
    • The set/coast switch
    • The cruise brake switch
    • The stop lamp switch
    • The throttle actuator control (TAC) motor
    • The vehicle speed sensor

Cruise Control Engaged

The cruise control system will engage and adjust vehicle speeds based on the activation of the following cruise control switches:

    • On/off
    • Resume/accel
    • Set/coast

The cruise control switches are located on the steering wheel.

The ECM/PCM monitors the signal circuits of the cruise control switches. The ECM/PCM uses the status of the cruise control switches in order to determine when to capture and maintain the selected vehicle speed. The ECM/PCM monitors the signal circuit of the vehicle speed sensor in order to determine the desired vehicle speed. The ECM/PCM uses the TAC motor in order to maintain the vehicle speed. For further information on the TAC system, refer to Throttle Actuator Control (TAC) System Description in Engine Controls - 2.2L (L61) or to Throttle Actuator Control (TAC) System Description in Engine Controls - 3.5L (L66).

Ignition positive voltage is supplied to the cruise control switches from the 2-ampere CRUISE fuse, located in the IPC fuse block. When the normally open cruise control on/off switch is switched ON , the switch closes and the ECM/PCM detects a high signal voltage on the cruise on switch signal circuit. The cruise control indicator, located on the cruise control on/off switch, will illuminate when the cruise control on/off switched is switched ON. To engage the cruise control system, turn the cruise control system ON by pressing the cruise control on/off switch ON and momentarily press the set/coast switch. When the set/coast switch is pressed, the normally open set/coast switch closes and the ECM/PCM detects a high signal voltage on the set/coast switch signal circuit. The ECM/PCM will confirm that the cruise control enable criteria has been met and then engage the cruise control system. The ECM/PCM will record the selected vehicle speed. Pressing the accelerator, 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 cruise control system 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 ECM/PCM 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 switch is momentarily pressed, with a minimum vehicle speed of 37 km/h (23 mph). Pressing 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 pressed, the normally open resume/accel switch closes and the ECM/PCM detects a high signal voltage on the resume/accel switch signal circuit. When the resume/accel switch is released, the ECM/PCM 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 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 pressed, with a maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed. Momentarily pressing the resume/accel switch, when the cruise control system has been disengaged by pressing the brake pedal, will recall the previous selected vehicle speed that is recorded in the ECM/PCM.

Cruise Control Disengaged

The ECM disengages the cruise control operation based on the signals from the following switches:

    • The on/off switch
    • The clutch start switch
    • The cruise brake switch
    • The stop lamp switch

The cruise brake switch, the clutch start switch, and the stop lamp switch are used to disengage the cruise control system. The stop lamp and cruise brake switch are incorporated into an assembly and are mounted to the brake pedal bracket. When the brake pedal is pressed, the normally closed cruise brake switch opens and the normally open stop lamp switch closes. The ECM/PCM detects a low signal voltage on the cruise brake signal circuit and detects a high signal voltage on the stop lamp switch signal circuit. When the clutch pedal is pressed, the normally closed clutch start switch opens and the ECM/PCM detects a low signal voltage on the clutch start switch signal circuit. The cruise control system will disengage when the cruise control on/off switch is switched to OFF. The vehicle speed stored in the memory of the ECM/PCM will be erased when the cruise control on/off switch is turned OFF, or the ignition switch is turned OFF.

The cruise control system will disengage when the ECM/PCM detects that a driver override function has been active for approximately 60 seconds.

Cruise Control Inhibited

The ECM inhibits the cruise control operation when any of the following conditions exist:

    • A cruise control related DTC has been set.
    • The antilock brake system/traction control system is active for more than 2 seconds.
    • The engine RPM is too low.
    • The engine RPM is too high.
    • The system voltage is not between 9 volts and 16 volts.
    • The vehicle speed is less than 40 km/h (25 mph).
    • The vehicle speed is too high.
    • The vehicle is in PARK, REVERSE, NEUTRAL, or 1st gear.