Cruise control is a speed control system that maintains a desired vehicle
speed under normal driving conditions. However, steep grades may cause variations
in the selected speeds.
The following are the main components of the cruise control system:
• | The cruise control module |
• | The cruise control ON/OFF switch |
• | The cruise control R/A switch |
• | The cruise control SET switch |
• | The powertrain control module (PCM) |
• | The stop lamp switch assembly |
• | The TCC brake switch/cruise control release switch |
The cruise control system uses the cruise control module assembly to maintain
the desired vehicle cruise speed and operation. The cruise control module assembly
has a controller and an electric stepper motor to vary the throttle in each different
cruise control mode. The controller monitors vehicle speed and operates the stepper
motor. The stepper motor operates in response to the controller, to maintain the
desired cruise speed. The electric stepper motor moves a strap that is attached
to the cruise control cable which moves the throttle linkage. The cruise control
module assembly contains a low speed limit which will prevent system engagement
below a minimum speed of 40 km/h (25 mph). The module assembly is not serviceable.
The operation of the controller is controlled by the function control switches
located on the multifunction turn signal lever. The cruise control functional control
switches include the ON/OFF, SET/COAST, R/A . The switch assembly provides driver
control of the cruise control system.
The cruise control release switch and stop lamp switch are used to disengage
the cruise control. A release switch assembly and a stop lamp switch assembly are
mounted on the brake pedal bracket . To disengage the system the driver presses
the brake pedal. The speed of the vehicle at brake actuation will be stored in the
memory of the cruise module.
With cruise control, you can maintain a speed of about 40 km/h (25 mph) or
more without keeping your foot on the accelerator. When the driver turns off the
on/off switch or ignition switch, the cruise control turns off. The vehicle speed
stored in the memory of the cruise module will be lost.
Ignition 3 voltage is supplied from the cruise control fuse, to the cruise
control module. The cruise control module is grounded to the chassis. When the cruise
control ON/OFF switch is on, ignition 3 voltage is applied to the cruise on switch
signal circuit of the cruise control module. If the driver has not pressed the brake
pedal, ignition 1 voltage is supplied through the ABS/TCC switch, to the TCC brake
switch signal circuit of the cruise control module. When the driver presses the
brake pedal, battery positive voltage is supplied from the stop lamp fuse, through
the closed stop lamp switch to the stop lamp switch supply voltage signal circuit
of the cruise control module. When the SET/COAST button is pressed , ignition positive
voltage is applied to the cruise control set/coast switch signal circuit of the
cruise control module. When pressing the R/A , ignition positive voltage is applied
to the cruise control resume/accelerate switch signal circuit of the cruise control
module.
The cruise control module receives a vehicle speed signal input from the powertrain
control module (PCM). In operation, the voltage varies between 0-5 V.
The cruise control module, cruise engaged circuit, sends a signal to the
PCM when cruise is engaged. The cruise control module, cruise inhibit signal circuit,
is a circuit used by the PCM to disengage cruise control when conditions inconsistent
with cruise operation are present.
After the cruise control engaged criteria has been met and the cruise ON and
Set/Coast have been commanded, the cruise control module sends a signal to the PCM
that the cruise control is engaged. The PCM then sends a class 2 message to the instrument
panel cluster (IPC) to illuminate the cruise indicator.
The PCM will inhibit cruise control:
• | When vehicle speed is less than 40 km/h (25 mph). |
• | When PARK, REVERSE, NEUTRAL, or 1st gear is indicated. |
• | With high engine RPM. e.g. fuel cut-off |
• | When vehicle speed is to high |
• | When an over or under charged battery voltage condition exists |
• | Antilock brake system/traction control system is active for more than
2 seconds |
• | A 6 mph or more decrease in non-drive wheel speed in 0.4 seconds with
out seeing the extended brake travel contacts of the TCC Brake switch transition. |
If the PCM determines that any of the cruise control inhibit conditions are
present, the PCM will disengage the cruise control . The PCM accomplishes this by
removing the ground from the cruise control inhibit signal circuit.