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 clutch pedal position (CPP) sensor, 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)

The BCM monitors the signal circuit of the cruise control switches. The BCM relays the cruise control switch status to the ECM via a serial data message. 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 and the desired vehicle speed. The ECM uses the TAC motor in order to maintain the vehicle speed. For further review of the TAC system, refer to Throttle Actuator Control (TAC) System Description .

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 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 the cruise control function switch being activated. When the normally open cruise control on/off switch is turned ON, the switch closes and the BCM sends a 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 switch closes and the BCM detects the predetermined voltage signal on the cruise control resume/accel and set/coast switch signal circuit. The BCM sends a serial data message to the ECM indicating that the + RES switch or the - SET switch is active. The + RES switch or the - SET switch will remain inactive when the BCM has not received the predetermined voltage signal from the on/off switch.

#### 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

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 serial data message to the driver information center (DIC) in order to display the CRUISE ENGAGED message.

Pressing the accelerator pedal while the cruise control system is engaged, allows 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, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed. Momentarily activating the + RES switch will recall the previous vehicle speed, after the cruise control system is disengaged by pressing the brake pedal.

#### Cruise Control Disengaged

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

• | The BPP sensor

• | The CPP sensor, if equipped with a manual transmission

• | The cruise control On/Off switch

The BPP sensor and the CPP sensor 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 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 . Pressing the clutch pedal while the cruise control is engaged will also disengage the Cruise Control System. The engine control module (ECM) monitors the CPP sensor via the CPP sensor signal circuit as the voltage signal decreases while the pedal reaches the fully applied position.

The cruise control system will also disengage when the cruise control on/off switch is switched OFF. The BCM sends a serial data message to the ECM in order to disengage the cruise control system. The vehicle speed stored in the memory of the engine control module 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 also 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 serial data message to the driver information center (DIC) in order to turn off the CRUISE ENGAGED message.

Every time the cruise control system is disengaged, the ECM will keep track of the reason for system disengagement. The last 8 disengagement reasons will be recorded within the ECM memory. The scan tool will display the last 8 Cruise Disengage History parameters, in which one out of approximately 50 possible reasons will be displayed in each of these 8 parameters. For the disengagement reason to be displayed within the scan tool parameter either the cruise control system is active and disengagement is requested, or engagement of the system is requested but a fault is present. For a list of each disengagement reason along with each definition, refer to Control Module References for the ECM Scan Tool Information.

#### Cruise Control Inhibited

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

• | The ECM has not detected a brake pedal activation from the body control module (BCM).

• | 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.