Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions. However, steep grades up or down 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 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 a controller and an electric stepper motor to vary the throttle in each different cruise control mode. Two important components in the module assembly help to do this. The first is the electronic controller and the second is an electric stepper motor. 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 stoplamp switch are used to disengage the cruise control. A release switch assembly and a stoplamp 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.
The vehicle speed sensor (VSS) is mounted to the automatic transaxle assembly and produces an AC signal. The frequency of this signal is proportional to the speed at which the automatic transaxle assembly output shaft rotates, which in turn is proportional to the speed of the vehicle. The AC signal is supplied to the powertrain control module (PCM). The PCM converts the number of pulses per mile per second to determine vehicle speed. The signal is then sent to the cruise control module assembly and speedometer assembly at a rate of 4000 pulses per mile.
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 positive 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 positive voltage is applied to the cruise on switch signal terminal of the cruise control module. If the driver has not pressed the brake pedal, ignition positive voltage is supplied through the cruise control release switch, to the cruise control brake pedal switch signal terminal 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 signal terminal of the cruise control module. 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 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.
The cruise control module, cruise indicator control terminal, sends a signal to the PCM when cruise is engaged. The cruise control module, cruise cancel signal terminal, is a circuit used by the PCM to inhibit cruise control when conditions inconsistent with cruise operation are present.
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 by the transaxle range switch |
| • | With low engine RPM |
| • | 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 |
If the PCM determines that any of the cruise control inhibit conditions are present, the PCM requests that the cruise control module disengage cruise control. The PCM accomplishes this request by opening the cruise control cancel signal circuit. If the cruise indicator control signal, sent by the cruise control module to the PCM, indicates that the cruise control is still engaged after the PCM has requested that the cruise control disengage, the PCM sets a DTC.
