Principles Of Operation

Cruise Control

Principles of Operation

Pressing and releasing the steering wheel cruise control 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 the respective switch is pressed and held, the vehicle speed continues to accelerate or decelerate until the switch is released.

Pressing and releasing the OFF switch, or turning the ignition switch to the OFF position, turns the cruise control system off. Pressing the brake pedal puts the cruise control system into the standby mode. Pressing the RESUME 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, the ignition switch is in the OFF position, 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.

The cruise control deactivator switch is provided as an additional safety feature. Normally, when the brake pedal is applied, an electrical signal is sent from the stoplamp circuit to the ABS module. The PCM receives a serial message over the High Speed Controller Area Network (HS-CAN) from the ABS module. The serial message indicates that the brake pedal has been applied and the PCM releases the throttle. 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 clockspring provides the electrical interface between the steering column wiring and the cruise control switch(es) in the steering wheel.

The inputs to the PCM are the:

- Output Shaft Speed (OSS) sensor
- Digital Transmission Range (TR) sensor
- Cruise control switches
- Stoplamp switch
- Cruise control deactivator switch
- ABS module
- Accelerator pedal position sensors

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 Electronic Throttle Control (ETC) subsystem.

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 the actual vehicle speed and the desired speed.

The PCM strategy uses the throttle control for smooth accelerations.

The PCM sends a serial message over the HS-CAN to the IC whenever the cruise control indicator should be turned on or off.

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

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

An ETC system fault also causes the cruise control system to be disabled. In this case, an ETC system warning indicator or a message center message is displayed.

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

- Transmission gear selector in a position other than D or OD.
- Cruise control set speed is overridden 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 48 km/h (30 mph).
- Cruise control switch pressed or stuck longer than 2 minutes.

Network Communication

The following cruise control system components communicate via the HS-CAN:

- PCM
- ABS module
- IC

While there are numerous messages internal to the cruise control system modules, the following messages are utilized by the cruise control system in conjunction with outside systems:

Module Communication Messages