For 1990-2009 cars

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at 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 brake pedal position (BPP) sensor

• | The instrument panel module (IPM)

• | The cruise control on/off switch

• | Engine control module (ECM)

• | Accel/resume switch

• | Set/coast switch

• | Throttle actuator control (TAC) motor

• | Vehicle speed sensor (VSS)

### 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

• | Accel/resume

• | Set/coast

The IPM monitors the cruise control switch signal circuit. The IPM sends the cruise control switch status to the engine control module (ECM) via the GMLAN serial data circuit. The ECM uses the cruise control switch status in order to determine when to capture and maintain the vehicle speed. The ECM monitors the vehicle speed signal circuit in order to determine the desired vehicle speed. The ECM uses the throttle actuator control (TAC) motor in order to maintain the vehicle speed. For further review of the TAC system, refer to Throttle Actuator Control (TAC) System Description or to Throttle Actuator Control (TAC) System Description .

Ignition voltage is supplied to the cruise control switch from the 2-ampere RUN/CRANK ELEC fuse located in the integrated IPM fuse block. The cruise control function switches are arranged in a resistive ladder design, with each cruise control function switch having a different resistance value. The IPM detects a specific voltage value that is associated with the cruise control function switch being activated. When the normally open cruise control On/Off switch is turned ON, the switch closes and the IPM detects a predetermined voltage signal on the cruise control set/coast and resume/accel switch signal circuit. The IPM sends a GMLAN serial data message to the ECM indicating that the on/off switch is active. Similarly, when the normally open accel/resume switch or the normally open set/ coast switch are pressed, the switch closes and the IPM detects the predetermined voltage signal on the cruise control set/coast and resume/accel switch signal circuit. To engage the cruise control system, ensure that the vehicle speed is above 40.2 km/h (25 mph), turn the cruise on/off switch ON and momentarily press the set/coast switch. The ECM will engage the cruise control system and record the vehicle speed. The ECM sends a GMLAN serial data message to the instrument panel cluster (IPC) in order to illuminate the Cruise indicator in the IPC. The set/coast switch or the accel/ resume switch will remain inactive when the IPM has not received the predetermined voltage signal from the on/off switch. 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 accel/resume switch. When the cruise control system is engaged, pressing and holding the set/coast button 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 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). Pressing and holding the accel/resume 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 accel/resume switch is released, the ECM 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 accel/resume switch will allow the vehicle to accelerate at 1.6 km/h (1 mph) increments for each time that the accel/resume switch is momentarily pressed, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed. Momentarily activating the accel/resume button, 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 ECM.

### Cruise Control Disengaged

The engine control module (ECM) disengages the cruise control operation based on the signals from the following switches:

• | The brake pedal position (BPP) sensor

• | The cruise control on/off switch

The BPP sensor is mounted on the brake pedal bracket. Pressing the brake pedal while the cruise control is engaged will disengage the cruise control system. The instrument panel module (IPM) monitors the BPP sensor via the brake pedal position sensor signal circuit. The IPM sends a GMLAN serial data message to the ECM indicating the position of the brake pedal. For further information on the BPP sensor, refer to Exterior Lighting Systems Description and Operation or to Brake Pedal Position Sensor Calibration .

When the cruise control On/Off switch is turned OFF, the cruise control system will disengage.

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

When the cruise control system has been disengaged, the ECM sends a GMLAN serial message to the instrument panel cluster (IPC) in order to turn off the Cruise indicator.

The vehicle speed stored in the memory of the ECM will be erased when the cruise control On/Off button, or the ignition switch is turned off.

### Cruise Control Inhibited

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

• | A Cruise Control System DTC has been set.

• | The vehicle speed is less than 40.2 km/h (25 mph).

• | The vehicle speed is too high.

• | The vehicle is in PARK, REVERSE, NEUTRAL, or 1st gear.

• | The engine RPM is too low.

• | The engine RPM is too high.

• | The system voltage is not between 9-16 volts.

• | The Antilock Brake System (ABS)/Traction Control System (TCS) is active for more than 2 seconds.