Cruise Control Description and Operation

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

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions. However, steep grades 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 clutch pedal position switch (CPP), if equipped
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 an electronic controller and an electric stepper motor to vary the throttle in each different cruise control mode. The electric controller monitors vehicle speed and operates the electric stepper motor. The stepper motor operates in response to the electronic 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 electronic controller is controlled by the function control switches located on the steering wheel. The cruise control functional control switches include the ON/OFF, SET/COAST and R/A (resume/accelerate) switch. The switch assembly provides driver control of the cruise control system. The TCC/Brake switch and stop lamp switch control the cruise control release signal and stoplamp signal. These signal circuits are used to disengage the cruise control. The switch assemblies are mounted on the brake pedal bracket. To disengage the system electrically the driver presses the brake pedal. The speed of the vehicle at brake actuation will be stored in the memory of the cruise module.

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 the 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 fuse, to the cruise control module. The cruise control switch is supplied ignition positive voltage by the cruise switch fuse. 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 circuit of the cruise control module. If the driver has not pressed the brake pedal, ignition positive voltage is supplied through the cruise control release circuit, to the cruise control release signal terminal of the cruise control module. On vehicles equipped with a manual transmission, a clutch switch is wired in series on this circuit and operates the same. 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. As this operation occurs, ignition positive voltage is removed from the cruise release signal circuit. If equipped, voltage is also removed from the cruise release signal circuit when the clutch pedal is pressed. 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 control module, cruise engaged 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.

After the cruise control engage criteria has been met and the cruise control ON and Set/Coast have been commanded, the cruise control module sends a signal to the PCM that the cruise control is engaged. The PCM sends a class 2 message to the BCM that the cruise control is engaged. The BCM sends a message to the instrument panel cluster (I PC) to illuminate the cruise light.

The PCM will inhibit cruise control:
- When vehicle speed is less than 40 km/h (25 mph)
- When in PARK, REVERSE, NEUTRAL, or 1st gear
- With low engine RPM
- With high engine RPM (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 will disengage the cruise control. The PCM accomplishes this by opening the cruise control inhibit signal circuit.