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 electronic cruise control system
has the capability to CRUISE, COAST, RESUME SPEED, ACCELERATE, and
TAP-UP or TAP-DOWN.
The main parts of the cruise control system are:
• | The cruise control module assembly |
• | The function control switches |
• | The cruise control release switch |
• | The stop lamp switch assembly |
• | The vehicle speed sensor |
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
control light.
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 opening the cruise control inhibit signal circuit.