The Stepper Motor Cruise Control (SMCC) is a speed control
system which maintains a desired vehicle speed under normal driving conditions.
However, steep grades up or down may cause variations in the selected speeds.
The system has the following capabilities:
An electronic controller and electric motor are contained in the cruise
control module. The controller monitors the vehicle speed and operates the
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 in order to vary the throttle position, maintaining the desired cruise
speed. The cruise control module contains a low speed limit which will prevent
system engagement below a minimum speed, approximately 40 km/h (25 mph).
Mode control switches located on the cruise control switch control the module.
The cruise control function is in standby disabled mode until all conditions
inconsistent with cruise control operation are cleared.
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 cruise control switch is on, 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 986 through the cruise control release switch, to circuit 86,
and to the cruise control module terminal D. If the brake pedal is
pressed, 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 must detect current flow
through the Center High-Mounted Stop Lamp (CHMSL) bulbs for the cruise control
to operate properly. When pressing Resume/Accelerate (R/A) on the steering
wheel control switch, battery voltage is applied through circuit 87
to terminal C of the cruise control module. When pressing Set/Coast
on the steering wheel control switch, battery voltage is present through circuit 84
to the cruise control module terminal B.
The clear switch is closed under normal operating procedures. When the
clear switch opens, the 12V signal through circuit 986 to the cruise
control release switch disengages.
The cruise control module terminal K is the vehicle speed signal
input terminal through circuit 817. In operation, the voltage varies
between 0-5V. The cruise control module terminal J is used to
signal the Powertrain Control Module (PCM) when 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, to inhibit cruise control when conditions
inconsistent with cruise operation are present.
The PCM will inhibit cruise control under the following conditions:
| • | When vehicle speed is less than 40 km/h (25 mph). |
| • | When PARK, REVERSE, NEUTRAL, or 1st gear is indicated by
the transaxle range switch. |
| • | When an over/under battery voltage condition exists. |
| • | With high engine RPM (fuel cut-off). |
