Cruise Control Description and Operation 3.4L

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at speeds above 40km/h (25 mph). However, steep grades may cause variations in the selected speeds. The main components of the cruise control system are:

The cruise control system has the capability to adjust speeds and disengage the system based on the activation of the following cruise control switches:

The cruise control module controls the operation of the cruise control system. The cruise control module monitors the signal circuits of the cruise control switches. When the normally open cruise On/Off switch closes with a switch activation, the cruise control modules detects a high voltage on the signal circuit. The cruise control module activates the cruise control system.The set/coast switch and the resume/accel switch will not operate the system when the cruise control module has not activated the system based on the cruise control on/off switch signal circuit .

The cruise control module monitors the cruise control set/coast switch in order to determine when to capture and maintain the vehicle speed. The cruise control module monitors the vehicle speed signal circuit in order to determine the desired speed. The PCM pulses the vehicle speed signal circuit at 4000 pulses per minute. After an initial set speed has been established, the cruise control module also uses the cruise control set/coast switch signal circuit in order to tap down the set speed when the cruise control module detects a switch activation.

The cruise control module monitors the cruise control resume/accel switch signal circuit in order to determine when to resume the previous set speed. This feature only works within the same ignition cycle and as long as the cruise wasn't turned off using the cruise control On/Off switch since the last cruise engagement. After the set speed has been resumed, the cruise control module also uses the cruise control resume/accel switch signal circuit in order to tap up the set speed when the cruise control module detects a switch activation.

The cruise control module assembly has a controller and an electric stepper motor to vary the throttle in each different cruise control mode. Two components in the module assembly help to do this. The electronic controller and the electric stepper motor. The controller monitors vehicle speed and operates the stepper motor. The stepper motor operates in response to the controller, to maintain the desired cruise speed. The electric stepper motor moves a strap that is attached to the cruise control cable which moves the throttle linkage.

The cruise control module grounds the cruise engaged signal circuit when cruise control is engaged. The PCM monitors the cruise engaged signal circuit in order to determine when the cruise control is engaged. The PCM sends a class 2 message indicating that the cruise control is engaged to the instrument panel cluster (IPC ) (Buick Only). The IPC illuminates the cruise indicator. The cruise control module, cruise cancel signal circuit, is a circuit used by the PCM to inhibit cruise control when conditions inconsistent with cruise operation are present.

The cruise control release switch and stoplamp switch are used to disengage the cruise control. A release switch assembly and a stoplamp switch assembly are mounted on the brake pedal bracket . To disengage the system the driver presses the brake pedal. The speed of the vehicle at brake actuation will be stored in the memory of the cruise module. The cruise control module uses that stored speed when the cruise control system operation is resumed.

The PCM determines when the vehicle operating conditions are not appropriate for cruise control operation. The PCM inhibits the cruise control operation when any of the following conditions occur:

When any of the conditions listed above are present, the PCM removes the ground from the cruise control inhibit signal circuit. The cruise control module monitors the cruise control inhibit circuit in order to disable the system. The PCM compares the status of the cruise control inhibit signal circuit to the status of the cruise control engaged signal circuit. If the cruise control engaged signal circuit indicates that the cruise control module has cruise control engaged while the the PCM is inhibiting cruise control operation, the PCM sets a DTC. The PCM also sends a class 2 message indicating that the cruise control is engaged to the IPC indicator, (if equipped).

Another feature, internal to the cruise control module is the lash learn feature. The cruise control module has the ability to learn and electronically compensate for up to 4mm of lash in the non-adjustable cruise control cable. The cruise control module maintains this adjustment and updates this information every 30 seconds.

Cruise Control Description and Operation 3.6L

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

The cruise control switches are located on the multifunction/turn signal lever.

The engine control module (ECM) monitors the signal circuits of the cruise control switches in order to determine when to capture and maintain the selected vehicle speed. The ECM uses the throttle actuator control (TAC) motor in order to control the vehicle speed. For further information on the TAC system, refer to Throttle Actuator Control (TAC) System Description in Engine Controls - 3.6L (LY7).

Ignition positive voltage is supplied from the 10-ampere CRUISE fuse to the cruise control switch via the ignition 1 voltage circuit. When the normally open cruise control on/off switch is turned ON, the switch closes and the ECM detects a high signal voltage on the cruise control on switch signal circuit. When the normally open set/coast switch is pressed, the switch closes and the ECM detects a high signal voltage on the cruise control set/coast switch signal circuit. To engage the cruise control system, turn the On/Off switch On and momentarily press the set/coast switch. The ECM will confirm that the cruise control enable criteria has been achieved. The ECM will engage the cruise control system and record the selected vehicle speed. The ECM sends a class 2 message to the instrument panel cluster in order to illuminate the cruise control indicator. 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 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 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). When the normally open resume/accel switch is activated, the switch closes and the ECM detects a high signal voltage on the cruise control resume/accel switch signal circuit. Activating 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 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 activating 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 activated, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed . Momentarily activating the resume/accel 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.

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

The TCC brake switch and the stop lamp switch are incorporated into an assembly and are mounted to the brake pedal bracket. Pressing the brake pedal while the cruise control is engaged will disengaged the cruise control system. The ECM monitors the TCC brake switch/cruise control release signal circuit and the stoplamp switch signal circuit. When the brake pedal is pressed, the normally closed TCC brake switch opens and the normally open stoplamp switch closes. The ECM detects a low signal voltage on the TCC brake switch/cruise control release signal circuit and detects a high signal voltage on the stop lamp switch signal circuit. The cruise control system will also disengage when the cruise control On/Off switch is turned Off. The vehicle speed stored in the memory of the ECM will be erased when the cruise control On/Off switch is turned to Off, or the ignition switch is turned off.

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

When the cruise control system is disengaged, the ECM sends a class 2 message to the instrument panel cluster (IPC) in order to deactivate the cruise control indicator.

The engine control module (ECM) inhibits the cruise control operation when any of the following conditions exist: