9-7X L6-4.2L (2008)
Cruise Control: Description and Operation
Cruise Control Description and Operation
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 speed.
The following are the main components of the Cruise Control System:
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The engine control module (ECM)
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The on/off switch
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The resume/accel switch
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The set/coast switch
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The torque converter clutch (TCC) brake/cruise release switch
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The stop lamp switch
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The throttle actuator control (TAC) motor
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The vehicle speed sensor (VSS)
Cruise Control Engaged
The Cruise Control System will engage and adjust the vehicle speed based on the activation of the following cruise control switches:
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On/off
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Resume/accel.
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Set/coast
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 (See: Powertrain Management/Computers and Control Systems/Description
and Operation/Throttle Actuator Control (TAC) System Description) for the 4.2L engine, or Throttle Actuator Control (TAC) System Description (See:
Powertrain Management/Computers and Control Systems/Description and Operation/Throttle Actuator Control (TAC) System Description) for the 5.3L
and 6.0L engines.
Ignition positive voltage is supplied from the 10-amp HVAC 1 fuse to the cruise control switch via a switched ignition 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 also sends a serial data message to the instrument panel cluster (IPC) to illuminate the cruise engaged 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 and maintain the vehicle speed as the new set vehicle speed.
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 and maintain the vehicle speed
as the new set vehicle speed. 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.
Cruise Control Disengaged
The engine control module (ECM) disengages the cruise control operation based on the signals from the following switches:
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The on/off switch
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The torque converter clutch (TCC) brake/cruise release switch
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The stop lamp switch
The TCC brake/cruise release switch and the stop lamp switch are incorporated into an assembly and are mounted to the brake pedal bracket. Pressing
