Principles Of Operation

Cruise Control

Principles of Operation

The cruise control system is controlled by the PCM. The cruise control system is designed to maintain a selected vehicle speed between 40 km/h (25 mph) and the maximum limited vehicle speed. The cruise control system is controlled by the steering wheel mounted switches (ON, OFF, SET+, SET- RES (without audio controls), and RESUME (with audio controls)), the stoplamp switch, the clutch pedal cruise control deactivator switch (manual transmission), stoplamp switch and the cruise control deactivator switch (integral to the stoplamp switch). The steering wheel mounted switches are hard-wired to the PCM through the clockspring.

The cruise control functions include:

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

Pressing and releasing the ON switch turns the cruise control system on. Pressing and releasing the SET+ or SET- switch while the vehicle is traveling at the desired speed activates 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. 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 the standby mode. Pressing the RES (without audio controls) or RESUME (with audio controls) switch when the cruise control system is in the standby mode causes the vehicle to accelerate to the last set speed. The RESUME switch does not function if the OFF switch is pressed or if the current vehicle speed is below the minimum operational speed.

The clutch pedal cruise control deactivator switch is used on vehicles equipped with a manual transmission. When the clutch pedal is applied with the vehicle cruise control system engaged, the normally closed switch opens and signals the PCM to deactivate the cruise control.

The cruise control deactivator switch is provided as an additional safety feature. When the brake pedal is applied, an electrical signal from the stoplamp circuit to the PCM deactivates the system. Under increased brake pedal effort, the cruise control deactivator switch opens and removes the ground signal from the PCM, releasing the throttle.

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

The inputs to the PCM are the:

- Output Shaft Speed (OSS) sensor
- Transmission Range (TR) sensor
- Accelerator Pedal Position (APP) sensor
- Cruise control switch
- Clutch pedal cruise control deactivator switch (manual transmission)
- Cruise control deactivator switch (integral to the stoplamp switch)
- Stoplamp switch

The outputs of 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 message over the High Speed Controller Area Network (HS-CAN) to the IPC whenever the cruise control indicator should be turned on or off.

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

The cruise control system provides self-diagnostics. The cruise control is disabled anytime an error is detected in the system. No IPC indicator or message center messages are displayed when faults occur. Fault codes are logged by the PCM.

An Electronic Throttle Control (ETC) system fault also causes the cruise control system to be disabled. In this case, an ETC system powertrain malfunction (wrench) warning indicator is displayed.

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

- Transmission gear selector in a position other than D or OD (automatic transmission)
- Vehicle clutch pedal is applied (manual transmission)
- Cruise control set speed is over-ridden with the accelerator pedal for a period longer than 5 minutes
- Vehicle speed loss from set speed of greater than 16 km/h (10 mph) occurs
- Vehicle speed falls below the minimum allowable limit of 40 km/h (25 mph)
- Parking brake is applied
- Cruise control switch is pressed or stuck for longer than 2 minutes