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 clutch pedal position switch (CPP), if equipped |
| • | The stoplamp 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 an electronic controller and an electric stepper motor
to vary the throttle in each different cruise control mode. The electric
controller monitors vehicle speed and operates the electric stepper motor.
The stepper motor operates in response to the electronic 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 electronic 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 and
R/A (resume/accelerate) switch. The switch assembly provides driver control
of the cruise control system.
The stop lamp switch controls both the cruise control release signal
and stoplamp signal. These signal circuits are used to disengage the cruise
control. The stoplamp switch assembly is mounted on the brake pedal bracket.
To disengage the system electrically 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 the ignition switch, the cruise
control turns off. The vehicle speed stored in the memory of the cruise
module will be lost.
Ignition positive voltage is supplied from the cruise fuse,
to the cruise control module and cruise control switch. The cruise control
module is grounded to the chassis. When the cruise control ON/OFF switch
is on, ignition positive 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 positive voltage is supplied through the TCC/Brake,
cruise control release circuit, to the cruise control release signal terminal
of the cruise control module. On vehicles equipped with a manual transmission,
a clutch pedal position switch is wired in series on this circuit and operates
the same. 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 signal terminal of the cruise control module.
As this operation occurs, ignition positive voltage is removed from the
cruise release signal circuit. If equipped, voltage is also removed from
the cruise release signal circuit when the clutch pedal is pressed. When
the SET/COAST is pressed on the control switch, ignition positive voltage
is applied to the set/coast switch signal terminal of the cruise control
module. When pressing the R/A (resume/accelerate) on the control switch,
ignition positive voltage is applied to the resume/ accelerate switch
signal terminal 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 V and 5 V.
After the cruise control engage criteria has been met and the cruise
control 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 will inhibit cruise control:
| • | When vehicle speed is less than 40 km/h (25 mph) |
| • | When in PARK, REVERSE, NEUTRAL, or 1st gear |
| • | With high engine RPM (fuel cut-off) |
| • | When vehicle speed is too high |
| • | When an over or under charged battery voltage condition exists |
| • | Antilock brake system/traction control system is active for more
than 2 seconds |
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 enable signal circuit.
