Ford Explorer: Cruise Control - Vehicles With: Adaptive Cruise Control With Lane Centering / Description and Operation - Cruise Control - System Operation and Component Description

System Operation

Adaptive Cruise Control

Network Message Chart

  Network Input Messages - ABS Module

  Network Input Messages - IPMA

  Network Input Messages - IPC

  Network Input Messages - PCM

ACC Operation

NOTE: For a complete illustration of the ACC indicators and graphic displays, refer to the Owner's Literature.

The ACC system functions much like a standard cruise control system. The ACC system automatically adjusts the vehicle speed to maintain a set distance gap from the front of the vehicle and the vehicle in the same path of travel. When the ACC system is on and is following a vehicle or a vehicle enters the same driving lane, a follow vehicle graphic is displayed in the message center.

The ACC with stop and go technology allows the vehicle to follow a lead vehicle to a stop. An indicator in the message center indicates the vehicle is in the stopped mode. If the lead vehicle moves from a stop within 3 seconds, the vehicle automatically resumes to the set speed. If the lead vehicle remains stopped for more than 3 seconds, the system resumes when the RES (resume) switch on the steering wheel is pressed or the driver taps the accelerator pedal. An indicator in the message center indicates the vehicle is in the RES (resume) mode. The vehicle automatically accelerates to the set speed.

The ACC with lane centering (if equipped) uses radar and camera sensors to assist in keeping the vehicle within the lane by applying a continuous assistance steering torque input toward the center of the lane. When the system is active in the Alert mode and the vehicle unintentionally drifts out of its lane, the system provides an alert by vibrating the steering wheel. In Aid mode, the system provides steering assistance by counter steering the vehicle back into the lane. For additional information,
Refer to: Lane Keeping System - System Operation and Component Description (419-07 Lane Keeping System, Description and Operation).

Intelligent ACC with traffic sign recognition (if equipped) has a number of speed warning levels that can be programmed. When this mode is selected, a bracket appears around the set speed and the detected speed limit sign in the information display. The system is designed to set the vehicle speed to the speed limit detected by the speed sign recognition system before the vehicle passes the speed limit sign. Refer to the Owner's Literature for additional information.

The ACC system does not activate if the vehicle speed is below 20 km/h (12 mph) or if a lead vehicle is not detected. If either of these occur, the message center displays ADAPTIVE CRUISE - SPEED TOO LOW TO ACTIVATE.

The cruise control deactivator switch (which is integral to the brake pedal) is an additional safety feature. When the brake pedal is applied, the cruise control system deactivator switch opens and removes the ground signal from the PCM input circuit, releasing the throttle and immediately deactivating the system.

The CCM is on a dedicated CAN with the IPMA. The IPMA acts as a gateway module and relays network messages and DTC information from the CCM to other modules that utilize the ACC system.

The CCM monitors the yaw rate signal from the ABS module and compares it to wheel speed and steering wheel angle signals. If the ABS module determines the yaw rate is invalid, the CCM disables the ACC. The message center displays the message COLLISION WARNING MALFUNCTION and/or ADAPTIVE CRUISE MALFUNCTION.

The CCM monitors the environment in front of the vehicle while active. If the radar beam is obstructed by a buildup of snow, ice, rain or other debris or the vehicle is driven in a desert environment with no other traffic for extended periods of time, the sensor triggers an ADAPTIVE CRUISE NOT AVAILABLE SENSOR BLOCKED SEE MANUAL message in the message center and disables the ACC. The ACC resumes once the obstruction is cleared and the radar is able to detect targets or upon a key cycle.

The ACC system does not engage properly if the front radar sensor is not aligned correctly and the message center displays FRONT SENSOR NOT ALIGNED. The ACC resumes once the radar is aligned and is able to properly detect targets.

The CCM radar vertical and horizontal alignment procedure is located in General Procedures. The horizontal alignment for the CCM is a calibration check performed by the scan tool to insure the CCM radar is pointed straight. The scan tool identifies this as, Alignment Offset with a horizontal specification of +/- 3.0 degrees offset. For additional information,
Refer to: Cruise Control Radar Alignment (419-03B Cruise Control - Vehicles With: Adaptive Cruise Control With Lane Centering, General Procedures).

The ABS module estimates brake temperature by monitoring applied brake pressure over a period of time and sends a message to the CCM when the estimated temperature is above a given threshold. An alarm sounds and the ACC system is deactivated until the estimated brake temperature returns to cooler operating conditions. This condition can happen in hilly or mountainous driving terrain.

Cruise Control Indicator

The ACC indicator located in the IPC illuminates a gray indicator lamp and displays the previous gap setting and SET graphic indicating the system is in standby mode. This notifies the driver the system is ready and the vehicle can be accelerated to the desired speed. A green ACC indicator illuminates when the system is active.

Steering Wheel Switch Function

The ACC steering wheel mounted switches are momentary contact switches that toggle up and down for the cruise control switch state. Pressing and releasing the steering wheel cruise control ON/OFF switch turns the cruise control system on. Pressing up SET+ and releasing the SET switch sets the vehicle's speed and stores the set speed in memory. The ACC indicator illuminates and the message center displays the set speed and gap setting graphic.

There are two ways to change the set speed. The first way is to accelerate or brake to the desired speed and press and release the SET cruise control switch until the desired set speed is shown on the message center. The second way is by tapping the SET+ or the SET- switch while in the set mode, increasing or decreasing the displayed set speed by 1.6 km/h (1 mph) per tap. If the respective button is pressed and held, the displayed set speed continues to increase or decrease until the button is released. The ACC system may apply the brakes to slow the vehicle down to the new set speed. The set speed displays continuously in the message center while the ACC system is active.

Pressing and releasing the OFF switch or switching the ignition to OFF, turns the ACC system off. The ACC set speed memory is erased.

Applying the brake pedal or pressing the X (cancel) switch puts the ACC system in standby mode and the last set speed is displayed in the message center with a strike-through. Pressing the RES button when the ACC system is in standby mode causes the vehicle to accelerate to the last set speed. The set speed continuously displays in the message center while the ACC system is active. The RES button does not function if the OFF button is pressed, the ignition is cycled off or if the current vehicle speed is below the minimum operational speed.

The ACC system has the capability for the driver to change from ACC to standard cruise control. The LH 5-way steering wheel switch is used to switch from the ACC system to standard cruise control system within the message center. For information on selecting the standard cruise control in the message center, refer to the Owner's Literature. Once the driver has selected the standard cruise control in the message center, the ACC indicator is replaced by the standard cruise control indicator. The vehicle no longer responds to lead vehicles or automatic braking. Upon the next ignition cycle, the vehicle defaults back to the ACC system.

Gap Setting

When a vehicle ahead enters the same lane or a slower vehicle is ahead in the same lane, the vehicle speed adjusts automatically to maintain a preset distance gap. Four horizontal bars with preset graph settings are displayed in the message center. Pressing up (decrease) or down (increase) on the steering wheel cruise control gap switch increases or decreases the distance from the vehicle ahead. If all of the bars are illuminated, this is the longest gap setting. If only one bar is illuminated, that is the shortest gap setting.

The vehicle maintains the distance gap to the vehicle ahead until:

• the vehicle ahead accelerates to a speed above the set speed.
• the vehicle ahead moves out of the lane or out of view.
• the vehicle speed falls below 20 km/h (12 mph).
• a new gap distance is set.

The distance gap can be overridden by applying the accelerator pedal. The follow vehicle graphic is not displayed in the message center and the green indicator illuminates. When the accelerator pedal is released, the ACC system returns to normal operation and the vehicle speed decreases to the set speed or a lower if following a vehicle ahead.

Deceleration Control

The CCM commands the ABS module, which controls the brakes, to automatically apply the brakes to slow the vehicle to maintain a safe distance to the vehicle in front.

Pre-Collision Assist System Operation

The pre-collision assist system is an additional safety feature on vehicles equipped with ACC. The system is active whether the ACC system is on or off. If the system detects a vehicle, pedestrian or other object in the vehicle path of travel, the system provides three levels of functionality:

• Visual and audible alert.
• Brake support.
• Active braking.

The system uses object detection information from the radar sensor integrated in the CCM and the forward-looking camera in the IPMA mounted on the front windshield below the rear view mirror. The CCM and the IPMA scan a designated area in front of the vehicle. Messages are sent between the CCM and the IPMA on dedicated CAN circuits, which determine whether an object, vehicle or pedestrian is in the path of travel, the approximate distance to the object and how fast the vehicle is approaching it.

Component Description

Steering Wheel Switches

The cruise control steering wheel mounted switches are momentary contact switches that toggle up and down for the switch state. The switches are an input to the SCCM.

Brake Switch

When the brake pedal is applied, an electrical signal from 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 input circuit releasing the throttle, immediately deactivating the system.

CCM

The CCM contains a radar sensing unit which measures the relative speed and the distance between the front of the vehicle and the vehicle being followed. The IPMA is responsible for requesting the PCM to increase vehicle speed and the ABS module to brake, when necessary.

All CCM Diagnostic Trouble Codes (DTCs) are sent to the IPMA on a dedicated private CAN. The IPMA acts as a gateway.

IPMA

The IPMA is mounted on the windshield, below the rear view mirror. The IPMA contains a forward-looking camera with a designated sight line in front of the moving vehicle. The camera detects and differentiates between an approaching object, vehicle or pedestrian in the path of travel. This information is shared with the CCM on a dedicated private CAN circuit.