Description & Operation

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Vehicles are equipped with air bag supplemental restraint system. Before attempting any repairs involving steering column, instrument panel or related components, see AIR BAG SAFETY PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in AIR BAG RESTRAINT SYSTEMS article.

CAUTION: When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions. However, steep grades may cause variations in selected speeds. Electronic cruise control system has capability to CRUISE, COAST, RESUME SPEED, ACCELERATE, and TAP-UP or TAP-DOWN. Main parts of the cruise control system are:

Cruise Control Module (CCM).
Cruise control switches.
Cruise control release switch.
Brakelight switch assembly.
Vehicle Speed Sensor (VSS).

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. 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 then moves the throttle linkage. The cruise control module assembly contains a low speed limit which will prevent system engagement below a minimum speed of 25 MPH (40 KM/H). The module assembly is not serviceable.

The operation of the controller is controlled by the function control switches located on the cruise control lever. The cruise control function control switches include the ON/OFF, SET/COAST, R/A (resume/accelerate) and CANCEL switches. The switch assembly provides driver control of the cruise control system.

The cruise control release switch, brakelight switch and CANCEL switch are used to disengage the cruise control. The release switch assembly and brakelight switch assembly are mounted on the brake pedal bracket, and the CANCEL switch is located on the cruise control lever. To disengage the system, the driver either presses the brake pedal or activates the CANCEL switch. The speed of the vehicle at brake actuation will be stored in the memory of the cruise control 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 25 MPH (40 KM/H) or more without keeping your foot on the accelerator. When the driver turns off the ON/OFF switch, ignition switch, or the CANCEL 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 brakelight fuse, through the closed brakelight switch to the brakelight 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 (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.

The cruise indicator control terminal of the cruise control module sends a signal to the PCM when cruise is engaged. The cruise cancel signal terminal of the cruise control module 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 under the following conditions:

When vehicle speed is less than 25 MPH (40 KM/H).
When Park, Reverse, Neutral, or 1st gear is indicated.
With low engine RPM.
With high engine RPM (fuel cut-off).
When vehicle speed is too high.
When an over/undercharged battery voltage condition exists.
Anti-Lock Brake System/Traction Control System (ABS/TCS) is active for more than 2 seconds.
A 6 MPH or more decrease in non-drive wheel speed in 0.4 seconds with out seeing extended brake travel contacts of cruise control release switch transition.

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.