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 capability to CRUISE, COAST, RESUME SPEED, ACCELERATE, TAP-UP and TAP-DOWN.
An electronic controller and electric motor are combined in the cruise control module. The controller monitors 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 to vary throttle position in order to maintain the desired cruise speed. The cruise control module contains a low speed limit which will prevent system engagement below a minimum speed, approximately 25 mph. The module is controlled by mode control switches. Cruise Control is in a "Standby Disabled" mode until all conditions inconsistent with cruise control operation are cleared.
The cruise control inhibit criteria where the PCM will "inhibit" cruise control are:
As with most of the computer-controlled systems on these vehicles, troubleshooting requires a qualified technician using a scan tool to extract Diagnostic Trouble Codes (DTCs) and to input test commands to the system. There are, however, some basic checks that can be made.
MAJOR SYSTEM COMPONENTS
Cruise Control Module
The cruise control system uses a cruise control module to obtain and hold any desired vehicle cruise speed above a minimum speed of 25 mph. The module contains the following components:
Cruise Control Cable
The cable provides a physical connection between the cruise control module and the engine throttle lever. The cruise control cable is adjustable. Simply spread the adjuster lock tabs and pull out the adjuster lock to disengage the cruise control cable adjuster lock. Slide the adjuster forward, away from the module. Without moving the throttle lever, remove as much cable slack as possible. Push in on the adjuster lock to lock up the adjustment.
The Vehicle Speed Sensor (VSS) is mounted to the automatic transaxle. The VSS provides a low voltage Alternating Current (AC) signal to the Powertrain Control Module (PCM). The PCM converts the AC signal to a pulse width modulated Direct Current (DC) signal. The signal is sent to the cruise control module at a rate of 4,000 pulse per mile.Cruise Control Release and Stoplamp Switches
The cruise control release switch and the stoplamp switch are used to disengage the cruise control system. The switches are mounted on the brake pedal bracket. The switches disengage the system electrically when the brake pedal is pressed.
The cruise control release switch and stoplamp switch are adjusted together. Incorrect adjustment of either of these switches may cause premature brake lining wear or incorrect cruise control system operation. Remove the underdash insulator panel at the brake pedal. Press the brake pedal fully. Push the switches into their retainers until the switches are fully seated. Pull the brake pedal fully rearward against the pedal stop until the audible click can no longer be heard. Verify that the cruise release switch and stoplamp switch contacts actuate at 0.125-0.500 inch of brake travel. Nominal activation of the stoplamp switch contacts occurs about 0.200 inch beyond the point of the cruise control switch activation.