Cruise Control Engaged

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

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 engine control module (ECM)/powertrain control module (PCM) monitors the signal circuit of the cruise control switches. The ECM/PCM uses the cruise control set/coast and resume/accelerate switch signal circuit in order to determine when to capture and maintain the vehicle speed. The ECM/PCM monitors the vehicle speed signal circuit in order to determine the vehicle speed. The ECM (3.6L and 5.3L) uses the throttle actuator control (TAC) motor in order to maintain the vehicle speed. The PCM (3.8L) uses the throttle actuator control (TAC) module and the TAC motor in order to maintain the vehicle speed. For further review of the TAC System, refer to one of the following:

Throttle Actuator Control (TAC) System Description for the 3.6L engine
Throttle Actuator Control (TAC) System Description for the 3.8L engine
Throttle Actuator Control (TAC) System Description for the 5.3L engine

Ignition voltage is supplied to the cruise control switch from the 2-amp CRUISE SW fuse located in the instrument panel (I/P) 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 ECM/PCM 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 amber cruise control on/off switch illuminates. The ECM/PCM also detects a predetermined voltage signal on the cruise control cruise control set/coast and resume/accel switch signal circuit indicating that the on/off switch is active. Similarly, when the normally open RES + switch or the normally open SET - switch are activated, the ECM/PCM detects the predetermined voltage signal on the cruise control set/coast and resume/accel switch signal circuit. To engage the Cruise Control System, press the cruise on/off button On and momentarily activate the SET - switch. The ECM/PCM will engage the Cruise Control System and the ECM (3.6L and 5.3L) or the throttle actuator control (TAC) module (3.8L) will record the vehicle speed. The ECM/PCM sends a serial data message to the instrument panel cluster (IPC) in order to activate the Cruise Engaged indicator. The SET - switch or the RES + switch will remain inactive when the ECM/PCM 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, activating 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 vehicle will maintain the current vehicle speed as the new vehicle set speed. Momentarily activating the SET - switch will allow the vehicle to decelerate at 1.6 km/h (1 mph) increments for each time that the SET - switch is activated. The minimum vehicle speed for the tap down function is 37 km/h (23 mph). Activating 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 vehicle will maintain the current vehicle speed as the new vehicle set speed. Momentarily activating 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 pressed. The tap up function will only accelerate the vehicle a 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 or activating the CANCEL switch.