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 powertrain control module (PCM) |
• | The cruise/brake switch |
• | The throttle actuator control (TAC) module |
• | 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:
The powertrain control module (PCM) monitors the cruise control set/coast and
resume/accelerate switch signal circuit in order to determine when to capture and
maintain the vehicle speed. The PCM monitors the vehicle speed sensor (VSS) signal
circuit in order to determine the vehicle speed. The PCM 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
Throttle Actuator Control (TAC) System Description
in Engine Controls - 3.4L.
The cruise control switches are located on the steering wheel.
Ignition voltage is supplied to the cruise control switch from the 2 ampere
CRUISE 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 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 PCM 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 resume/accel switch or the set/coast switch are activated,
the PCM detects the predetermined voltage signal on the cruise control set/coast and
resume/accel switch signal circuit. To engage the Cruise Control System, turn the
Cruise Control System ON by momentarily activating the cruise On/Off button On and
momentarily activating the set/coast switch. The PCM will engage the Cruise Control
System and the TAC module will record the vehicle speed. The set/coast switch or the
resume/accel switch will remain inactive when the 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/coast switch and the resume/accel switch. When the Cruise Control System is
engaged, activating 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 vehicle will maintain the current vehicle
speed. When the Cruise Control System is engaged, momentarily activating 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 switch is activated, with the minimum vehicle speed
being 37 km/h (23 mph). 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 vehicle will maintain the current 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 pressed, with the maximum vehicle speed total
of 16 km/h (10 mph) over the current set vehicle speed . Momentarily
activating the resume/accel switch will recall the previous vehicle speed, after the
Cruise Control System is disengaged by pressing the brake pedal.
Cruise Control Disengaged
The powertrain control module (PCM) disengages the cruise control operation
based on the information received from the throttle actuator control (TAC) module.
The TAC module and the PCM monitors the signal circuits of the following switches:
• | The cruise/brake switch |
The cruise/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 PCM monitors the
stop lamp switch signal circuit and the TAC module monitors the TCC brake switch/cruise
control release signal circuit. When the brake pedal is pressed, the normally closed
cruise/brake switch opens and the normally open stoplamp switch closes. The PCM detects
a high signal voltage on the stop lamp switch signal circuit and the TAC module detects
a low signal voltage on the TCC brake switch/cruise control release signal circuit.
The PCM sends a UART serial data message to the TAC module indicating the status of
the stop lamp switch. 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
TAC module 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 PCM detects that the driver
has the accelerator pedal override active for approximately 60 seconds.
Cruise Control Inhibited
The powertrain control module (PCM) inhibits the cruise control operation when
any of the following conditions exist:
• | A Cruise Control System related DTC has been set. |
• | The vehicle speed is less than 40 km/h (25 mph). |
• | The vehicle is in PARK, REVERSE, NEUTRAL, or 1st gear. |
• | The engine RPM too low. |
• | The engine RPM is too high. |
• | The vehicle speed is too high. |
• | The system voltage is not between 6-16 volts. |
• | The Antilock Brake System (ABS)/Traction Control System (TCS) is active
for more than 2 seconds. |