The Stepper Motor Cruise Control (SMCC) is a speed control
system which maintains a desired vehicle speed under normal driving conditions.
Steep grades up or down may cause variations in the selected speeds. The
system has the following capabilities:
The cruise control module contains the following components:
| • | An electronic controller -- Monitors the vehicle speed and
operates the electric motor. |
| • | An electric motor -- In response to the controller, the motor
moves a connecting strap that is attached to the cruise control cable. |
The cable moves the throttle linkage to vary the throttle position in
order to maintain the desired cruise speed.
The cruise control module contains a low speed limit which will prevent
a system engagement below a minimum speed, approximately 40 km/h (25 mph).
The module is controlled by mode control switches located on the cruise
control switch. The cruise control is in a standby disabled mode until all
of the conditions inconsistent with the cruise control operation are cleared.
The ignition voltage is supplied from the CRUISE Fuse, through circuit 341
to terminal F of the cruise control module. The cruise control module
receives ground at terminal E, through circuit 1750 and from
G201.
When the slider switch is moved to the ON position, the battery voltage
is applied through circuit 397 to terminal A of the cruise control
module connector.
If the brake pedal is not pressed, battery voltage is present from
circuit 341 through the cruise control release switch and circuit 86
to the cruise control module terminal D.
If the brake pedal is depressed, battery voltage is supplied from the
STOP LAMP Fuse, through circuit 140, the stop lamp switch and circuit 17
to the cruise control module terminal G.
Terminal G needs current flow through the center high-mounted
stop lamp (CHMSL) bulbs in order to enable the cruise to operate (disable)
properly. When the slider switch is moved to the R/A (Resume/Accelerate)
position, the battery voltage is applied through circuit 87 to terminal C
of the cruise control module.
With the SET switch pressed, the battery voltage is present through
circuit 84 to the cruise control module terminal B. The cruise control
module terminal K is the speed signal terminal through circuit 817.
In operation, the voltage will oscillate between a high of 4-5 volts
and a low of near ground.
The cruise control module terminal J is used to signal the powertrain
control module (PCM) when the cruise control is engaged through circuit 85.
The PCM will then determine the correct shift pattern for the transmission.
The cruise control module terminal H is used by the PCM through circuit 83
in order to inhibit the cruise control when the conditions are inconsistent
with the cruise operation are present.
The following are the cruise control inhibit criteria:
| • | The vehicle speed is less than 40 km/h (25 mph). |
| • | The transaxle range switch indicates one of the following gears
positions: |
| • | An over/under battery voltage condition exists. |
| • | The engine RPM is high (fuel cut-off). |
