H2 V8-6.2L (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 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:
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The accelerator pedal
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The stop lamp switch
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The body control module (BCM)
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The cruise control switches
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The engine control module (ECM)
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The throttle actuator control (TAC) motor
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The vehicle speed sensor (VSS)
The body control module (BCM) monitors the signal circuit of the cruise control switches. The BCM relays the cruise control switch status to the engine
control module (ECM) via the serial data circuit. The ECM uses the status of the cruise control switch to determine when to capture and maintain the
vehicle speed. The ECM monitors the vehicle speed signal circuit in order to determine the desired vehicle speed. The ECM uses the throttle actuator
control (TAC) motor in order to maintain 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) .
Voltage is supplied to the cruise control switch via the steering wheel control switch reference voltage circuit supplied by the BCM. The cruise control
function switches are arranged in a resistive ladder design, with each cruise control function switch having a different resistance value. The BCM 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 BCM supplies a ground to the cruise control switch ON indicator circuit and it becomes illuminated. The BCM
sends a serial data message to the ECM indicating that the on/off switch is active. Similarly, when the normally open + RES switch or the normally open
- SET switch are pressed, the switch closes and the BCM detects the predetermined voltage signal on the cruise control set/coast and resume/accel switch
signal circuit. The BCM sends a serial data message to the ECM indicating that the + RES switch or the - SET switch is active. The - SET switch and the
+ RES switch will remain inactive when the BCM has not received the predetermined voltage signal from the on/off switch.
Cruise Control Engaged
The Cruise Control System will engage and adjust vehicle speeds, based on the activation of the following cruise control switches, which are located on
the steering wheel:
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The on/off switch
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The + RES switch
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The - SET switch
To engage the Cruise Control System, ensure that the vehicle speed is above 40.2 km/h (25 mph), turn the cruise On/Off switch ON and momentarily
press the - SET switch. The ECM will engage the Cruise Control System and record the vehicle speed. The ECM sends a serial data message to the
instrument panel cluster (IPC) in order to illuminate the Cruise Engaged indicator in the IPC.
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 previously
set 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,
pressing 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 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 switch will allow the vehicle to decelerate at 1.6 km/h (1 mph) increments for
each time that the - SET is momentarily pressed, with a minimum vehicle speed of 37 km/h (23 mph). Pressing 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 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 + RES switch will allow the vehicle to accelerate at 1.6 km/h (1 mph) increments for each time that the + RES
switch is momentarily pressed, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed.
If the cruise control system is disengaged by pressing the brake pedal or by activating the CANCEL switch, momentarily activating the + RES switch
will recall the previous vehicle speed.
Cruise Control Disengaged