For 1990-2009 cars

### Cruise Control Description and Operation

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 clutch pedal position (CPP) switch, if equipped with manual transmission

• | The body control module (BCM)

• | The cruise control On/Off switch

• | The + RES switch, equivalent to an accel/resume switch.

• | The - SET switch, equivalent to a set/coast switch.

• | The engine control module (ECM)

• | The throttle actuator control (TAC) motor

• | The 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

• | + RES

• | - SET

The BCM monitors the signal circuit of the cruise control switches. The BCM relays the cruise control switch status to the ECM via the GMLAN serial data circuit. The ECM uses the status of the cruise control switch to determine when to capture and maintain the vehicle speed. The ECM monitors the vehicle speed signal circuit in order to determine the vehicle speed. The ECM uses the TAC motor in order to maintain the desired vehicle speed. For further review of the TAC System, refer to Throttle Actuator Control (TAC) System Description for the 2.0L engine. Ignition voltage is supplied to the cruise control switch from the 2-ampere CRUISE fuse located in the integrated BCM fuse block. The cruise control switches are located on the steering wheel. The cruise control function switches are arranged in a resistive ladder design, with each cruise control function switch having a different resistance value. The BCM detects a specific voltage value that is associated with any cruise control function switch being activated. When the normally open cruise control On/Off switch is turned ON, the switch closes and the BCM detects a predetermined voltage signal on the cruise control set/coast and resume/accel switch signal circuit. The BCM sends a GMLAN serial data message to the ECM indicating that the On/Off switch is active. Similarly, when the normally open + RES switch or the normally open - SET switch are pressed, the BCM 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 switch. The ECM will engage the Cruise Control System and record the vehicle speed. The ECM sends a GMLAN serial data message via the BCM to the driver information center (DIC) in order to activate the CRUISE ENGAGED message. The - SET switch and the + RES switch will remain inactive when the BCM 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 switch and the + RES switch. When the Cruise Control System is engaged, pressing and holding the - SET switch will allow the vehicle to decelerate from the current set vehicle speed without deactivating the Cruise Control System. When the - SET 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 switch will allow the vehicle to decelerate at 1.6 km/h (1 mph) increments for each time that the - SET is momentarily pressed, with a minimum vehicle speed of 37 km/h (23 mph). Pressing and holding the + RES 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 + RES 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 + RES switch will allow the vehicle to accelerate at 1.6 km/h (1 mph) increments for each time that the + RES switch is momentarily pressed. Momentarily pressing the + RES 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 ECM.

#### Cruise Control Disengaged

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

• | The BPP sensor

• | The CPP switch

• | The cruise control On/Off switch

The BPP sensor and the CPP switch are used to disengage the Cruise Control System. 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 BCM monitors the BPP sensor via the brake pedal position sensor signal circuit. The BCM 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 clutch pedal is applied, the normally opened CPP switch closes and the ECM detects a high signal voltage on the CPP switch signal circuit. The Cruise Control System will disengage when the cruise control On/Off switch is switched OFF, or when the ECM detects that a driver override function has been active for approximately 60 seconds.

The vehicle speed stored in the memory of the ECM 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 ECM sends a GMLAN serial data message via the BCM to the DIC in order to turn OFF the CRUISE ENGAGED message.

#### 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.