Rainier 2WD L6-4.2L VIN S (2005)
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 speeds.
The following are the main components of the cruise control system:
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The powertrain control module (PCM)
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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 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 cruise control switches are located on the multifunction/turn signal lever.
The powertrain control module (PCM) monitors the signal circuits of the cruise control switches in order to determine when to capture and maintain
the selected vehicle speed. The PCM uses the throttle actuator control (TAC) module motor in order to control the vehicle speed. For further
information on the TAC system, refer to Throttle Actuator Control (TAC) System Description in Computers and Control Systems - 4.2L.
Ignition positive voltage is supplied from the 10-amp HVAC 1 fuse to the cruise control switch via the ignition 3 voltage circuit. When the normally
open cruise control On/Off switch is turned ON, the switch closes and the PCM 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 PCM 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 PCM
will confirm that the cruise control enable criteria has been achieved. The PCM will engage the cruise control system and record the selected vehicle
speed. The PCM sends a class 2 message to the instrument panel cluster (IPC) in order to illuminate the cruise control 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 PCM 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/Coast switch will allow the vehicle to decelerate at
1 mph increments for each time that the Set/Coast is momentarily pressed, with a minimum vehicle speed of 23 mph. When the normally open
Resume/Accel switch is activated, the switch closes and the PCM 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 PCM will record the vehicle speed and maintain the vehicle
speed as the new set vehicle speed. When the cruise control system is engaged, momentarily activating the Resume/Accel switch will allow the vehicle
to accelerate at 1 mph increments for each time that the Resume/Accel switch is momentarily activated, with the maximum acceleration total of 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 PCM.
Cruise Control Disengaged
The powertrain control module (PCM) 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 switch
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The stop lamp switch
The TCC 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 TCC brake switch/cruise control release
signal circuit and the stop lamp switch signal circuit. When the brake pedal is pressed, the normally closed TCC brake switch opens and the normally
open stop lamp switch closes. The PCM detects a low signal voltage on the TCC brake switch/cruise control release signal circuit and detects a high
signal voltage on the stop lamp switch signal circuit. The cruise control system will disengage when the cruise control On/Off switch is turned OFF.
The vehicle speed stored in the memory of the PCM 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.
