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 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 brake pedal position (BPP) sensor |
• | The body control module (BCM) |
• | 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:
The engine control module (ECM) monitors the signal circuit of the cruise control
switches. The ECM 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 monitors the vehicle speed signal circuit in order to determine the vehicle speed.
The ECM uses the throttle actuator control (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
- 3.6L.
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 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 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 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 will engage the
Cruise Control System and the ECM will record the vehicle speed. The ECM sends a class 2
message to the instrument panel cluster (IPC) in order to activate the Cruise indicator.
The SET - switch or the RES + switch will remain inactive when the ECM 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. When the Cruise Control
System is engaged, 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.
When the Cruise Control System is engaged, 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.
Cruise Control Disengaged
The engine control module (ECM) disengages the cruise control operation based
on the signals from one of the following:
• | The brake pedal position (BPP) sensor |
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
body control module (BCM) monitors the BPP sensor via the brake pedal position sensor
signal circuit. The ECM detects a high voltage signal on stop lamp switch signal circuit
from the BCM indicating that the brake pedal has been pressed. For further information
on the BPP, refer to
Exterior Lighting Systems Description and Operation
and to
Brake Pedal Position Sensor Calibration
in Lighting Systems.
When the cruise control on/off switch is turned OFF, the Cruise Control System
will disengage.
The Cruise Control System will disengage when the ECM detects that a driver
override function has been active for approximately 60 seconds.
When Cruise Control System has been disengaged, the ECM sends a class 2
message to the instrument panel cluster (IPC) in order to turn off the Cruise indicator.
The vehicle speed stored in the memory of the ECM will be erased when the Off
button is activated, or the ignition switch is turned OFF.
Cruise Control Inhibited
The engine control module (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 within 9-16 volts. |
• | The Traction Control System (TCS) is active for more than 2 seconds. |
Cruise Control Description and Operation 3.8L
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 brake pedal position (BPP) sensor |
• | The body control module (BCM) |
• | The powertrain control module (PCM) |
• | 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 signal circuit of the cruise
control switches. The 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 PCM monitors the vehicle speed 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 - 3.8L.
Ignition voltage is supplied to the cruise control switch from the 2-amp 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
amber cruise control on/off switch illuminates. The 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 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 - switch. The PCM will engage the Cruise Control System and the TAC
module will record the vehicle speed. The PCM sends a class 2 message to the
instrument panel cluster (IPC) in order to activate the Cruise indicator. The SET -
switch or the RES + switch will remain inactive when the ECM 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. When the Cruise Control System is engaged,
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. When the Cruise
Control System is engaged, 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.
Cruise Control Disengaged
The powertrain control module (PCM) disengages the cruise control operation
based on the signals from one of the following:
• | The brake pedal position (BPP) sensor |
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
body control module (BCM) monitors the brake pedal position sensor via the BPP sensor
signal circuit. The PCM detects a high voltage signal on stop lamp switch signal circuit
from the BCM indicating that the brake pedal has been pressed. For further information
on the BPP sensor, refer to
Exterior Lighting Systems Description and Operation
and to
Brake Pedal Position Sensor Calibration
in Lighting Systems.
When the cruise control on/off switch is turned OFF, the Cruise Control System
will disengage.
The Cruise Control System will disengage when the PCM detects that a driver
override function has been active for approximately 60 seconds.
When Cruise Control System has been disengaged, the PCM sends a class 2
message to the instrument panel cluster (IPC) in order to turn off the Cruise indicator.
The vehicle speed stored in the memory of the throttle actuator control (TAC)
module will be erased when the Off button is activated, or the ignition switch is
turned OFF.
Cruise Control Inhibited
The powertrain control module (PCM) 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 within 9-16 volts. |
• | The Traction Control System (TCS) is active for more than 2 seconds. |