System Operation
Network Message Chart
Module Network Input Messages - IPMA
| Broadcast Message | Originating Module | Message Purpose |
|---|---|---|
| ABS active | ABS module | Disables the lane keeping alert during an ABS activation. |
| Camera heater status | BCM | Provides the current camera heater status to the IPMA. |
| Lane keeping system enable/disable request | IPC | Used to enable and disable the lane keeping alert based on the lane keeping system switch input from the driver. |
| Lane keeping system menu status | IPC | Used to communicate the current lane keeping alert sensitivity and intensity message center selections. |
| Power mode | BCM | Enables and disables the IPMA based on the ignition switch position. |
| Stability/traction control indicator request | ABS module | Disables the lane keeping alert during a traction on stability control intervention. |
| Steering angle | SASM | Used to communicate current steering wheel angle. |
| Steering wheel vibration motor status | BCM | Used to communicate the status of the steering wheel vibration motor. |
| Transmission gear lever position | PCM | Used on gasoline vehicles to enable and disable the IPMA based on the selector lever position. |
| Transmission gear lever position | TCM | Used on diesel vehicles to enable and disable the IPMA based on the selector lever position. |
| Turn signal status | BCM | Suppresses the lane keeping alert on the side of the vehicle corresponding to a turn signal activation. |
| Vehicle yaw rate | RCM | Disables the lane keeping alert in the event that the yaw rate of the vehicle exceeds a predetermined threshold. |
| Vehicle lateral acceleration | RCM | Disables the lane keeping alert in the event that the lateral acceleration of the vehicle exceeds a predetermined threshold. |
| Vehicle speed | ABS module | Enables the lane keeping alert when the vehicle speed is above 64 km/h (40 mph). |
| Wiper speed information | BCM | Provides windshield wiper status information to the IPMA. |
Module Network Input Messages - BCM
| Broadcast Message | Originating Module | Message Purpose |
|---|---|---|
| Camera heater request | IPMA | Request to turn the camera windshield defrost heater grid on or off based on feedback from the IPMA camera. |
| Lane keeping alert request | IPMA | Request to provide steering wheel haptic feedback (vibration) from the steering wheel vibration motor when a lane departure is detected. |
Module Network Input Messages - IPC
| Broadcast Message | Originating Module | Message Purpose |
|---|---|---|
| Lane keeping alert request | IPMA | Used to generate the lane keeping alert visual warnings and the overhead vehicle status graphic in the message center. |
| Lane keeping alert system status display | IPMA | Used to communicate the current IPMA settings for lane keeping alert sensitivity and intensity. |
| Lane keeping system switch position | BCM | Used to communicate the lane keeping system switch position, as received by the BCM from the SASM on the LIN. |
System Operation
The lane keeping alert is turned on and off using the lane keeping system switch on the LH steering column multifunction switch. The LH steering column multifunction switch is directly connected to the SASM. When the ignition is ON, the SASM monitors the lane keeping system switch position and communicates the switch position to the BCM via the LIN circuit. The BCM sends the lane keeping system switch position message to the IPC on the MS-CAN. The IPC determines the current lane keeping system status and sends the lane keeping system enable/disable request to the IPMA through the MS-CAN and HS-CAN, with the BCM serving as a gateway.
The last known on/off setting for the lane keeping system is recalled every time the key is turned on. When the system is on, it is active only when the vehicle speed is above 64 km/h (40 mph) and at least one lane marking can be detected by the camera. The system can be turned off at any time by pressing the lane keeping system switch.
The system can be temporarily suppressed at any time by the following:
- Rapid braking or acceleration
- ABS activation
- Stability or traction control system activation
- Using the turn signal indicator
System Alerts
The system provides feedback to the driver though steering wheel vibrations and IPC message center visual alerts. When the system is active and a lane departure is detected by the IPMA, the IPMA sends the lane keeping alert request message to the BCM through the HS-CAN. Upon receipt of the message, the BCM activates the steering wheel vibration motor via the LIN circuit and gateways the lane keeping alert request message to the IPC through the MS-CAN. When the IPC receives the lane keeping alert request message, it generates the visual alert by turning the appropriate lane marking red in the IPC message center. Refer to System Display.
System Display
When the lane keeping system is turned off, an indicator remains illuminated in the IPC message center.
When the lane keeping system is turned on, an overhead graphic of a vehicle and lane markings is displayed in the IPC message center. When the system is active, the color of the lane markings changes from gray to green or red to indicate the current system status.
Gray: The system is inactive and temporarily unable to provide a lane keeping alert on the indicated side(s). This may be caused by:
- The vehicle speed is under the activation limit
- Too close to lane markings
- Lane markings are too narrow or wide
- Road has no or poor lane markings in the camera field-of-view
- Following vehicle in front too closely
- IPMA camera blocked
- Windshield dirty or damaged
- Standing water on road
- Lighting conditions (significant sun angles, high sunload on the camera, shadows, snow, heavy rain or fog)
- Turn signal is active
- Vehicle is in a dynamic maneuver
- Tight curves on the road
- ABS active
- Stability or traction control active
Green: The system can detect at least one lane marking and is available and ready to provide a lane keeping alert activation on the indicated side(s).
Red: The system is providing or has just provided a lane keeping alert activation on the indicated side(s).
Camera Windshield Defrost Heater
The camera windshield defrost heater keeps the windshield in front of the IPMA clear of frost and ice. The IPMA uses input from the front camera to determine when to request the heater on and off. When the IPMA detects that the image from the front camera image has not changed for a predetermined amount of time, the IPMA determines that the camera is blocked and sends the camera heater request message to the BCM. The BCM supplies voltage and ground to the camera windshield defrost heater based on the camera heater request message from the IPMA.
Message Center Settings
The system has 2 optional setting menus available through the message center Driver Assist menu. The last-known selection for each setting is stored by the IPMA and does not need to be set again after the key is cycled.
The Sensitivity setting affects how close to the lane markings the vehicle can be before a lane keeping alert is generated. Available options are:
- Normal
- Increased - Moves the alert zone closer to the vehicle
The Intensity setting allows the driver to select the intensity of the steering wheel vibration. Available options are:
- Low
- Normal
- High
Camera Alignment
Camera alignment is required for the lane keeping alert to function correctly. The procedure is initiated using the diagnostic scan tool and requires about 10 minutes of driving above 64 km/h (40 mph) to complete. If the alignment is unsuccessful, check the IPMA for proper installation. The IPMA camera alignment procedure should be performed when any of the following occur:
- Windshield replacement
- Change in tire size
- Suspension repair or alignment
- Front air bag deployment
- IPMA replacement
Component Description
IPMA
The IPMA communicates on the HS-CAN and controls the lane keeping system. The IPMA contains a forward-looking camera that is used to detect the position of the vehicle within the lane. The IPMA requires PMI and camera alignment when replaced.
Camera Windshield Heater
The camera windshield heater is a resistive-type heater grid that is adhered to the inside of the windshield directly in front of the IPMA camera.
Lane Keeping System Switch
The lane keeping system switch is a momentary contact switch located on the LH steering column multifunction switch. The lane keeping system switch inputs directly to the SASM, which forwards the switch state message to the BCM via a LIN.
Steering Wheel Vibration Motor
The steering wheel vibration motor is integral to the steering wheel. It is controlled by the BCM via a LIN circuit that is also shared with the SASM.