Principles Of Operation

Cruise Control

Principles of Operation

Pressing and releasing the ON switch turns the cruise control system on. Pressing and releasing the SET +/- switch while the vehicle is traveling at the desired speed activates the cruise control system.

The cruise control functions include:

- turning on the cruise control system
- setting and maintaining the desired vehicle speed
- accelerating the vehicle speed
- decelerating the vehicle speed
- turning off the cruise control system

Tapping the SET+ or the SET- switch while in the set mode increases or decreases the maintained vehicle speed by 1.6 km/h (1 mph) per tap, respectively. If either switch is pressed and held, the vehicle speed continues to accelerate (SET+) or decelerate (SET-) until the switch is released.

Pressing and releasing the OFF switch, or switching the ignition switch to the OFF position, turns the cruise control system off. Applying the brake pedal puts the cruise control system into standby mode. Pressing the RES switch when the cruise control system is in standby mode causes the vehicle to accelerate to the last set speed. The RES switch does not function if the OFF switch is pressed or if the current vehicle speed is below the minimum operational speed.

Whenever the cruise control system is engaged and active, a cruise control icon on the Instrument Cluster (IC) is illuminated.

When the brake pedal is applied, an electrical signal from the stoplamp switch is sent to the PCM to deactivate the cruise control system. The cruise control deactivator switch, which is integral to the stoplamp switch, is provided as an additional safety feature. Under increased brake pedal effort, the cruise control deactivator switch opens and removes the voltage signal from the PCM input circuit, deactivating the cruise control system.

The ABS module monitors brake pressure and also receives an electrical signal from the stoplamp switch. A fault in the ABS module can disable the cruise control system.

The clockspring provides the electrical interface between the steering column wiring and the cruise control switches in the steering wheel.

The inputs to the PCM are the:

- Output Shaft Speed (OSS) sensor
- Digital Transmission Range (TR) sensor
- Cruise control switch
- Stoplamp switch
- Cruise control deactivator switch
- Accelerator Pedal Position (APP)

The outputs from the PCM are the:

- Cruise control indicator lamp
- Throttle command

The cruise control system throttle position is completely controlled by the PCM through the electronically-controlled throttle body. Cruise control electronics are contained entirely within the PCM.

When the cruise control system is active, the PCM corrects for deviations in the actual vehicle speed by proportionally moving the throttle plate. The PCM modulates the throttle to minimize error between actual and desired vehicle speed.

The PCM strategy uses the throttle control for smooth accelerations.

The PCM sends a serial message over the High Speed Controller Area Network (HS-CAN) to the IC to command the cruise control indicator on or off.

In the event of an off command or a deactivation request from any source, the system carries out a hard deactivation and immediately returns the throttle to the idle position.

The cruise control system provides self-diagnostics. The cruise control system disables operation and sets a PCM DTC if it detects certain faults. The IC does not indicate cruise control faults with a indicator or message center message. Fault codes are logged by the PCM.

Additionally, the following conditions cause the cruise control system to deactivate:

- The transmission gear selector is in a position other than D or OD.
- The cruise control set speed is overridden with the accelerator pedal for longer than 5 minutes.
- Vehicle speed loss from set speed of greater than 16 km/h (10 mph) occurs.
- The vehicle speed falls below the minimum allowable limit 40 km/h (25 mph).
- A cruise control switch is pressed or stuck longer than 2 minutes.
- ABS system fault