Lane Departure Warning (LDW+)

WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

The purpose of the Lane Departure Warning (LDW+) system is to provide a warning alert to the driver in case of an unintended lane departure (i.e the driver did not use turn signals beforehand to confirm a planned lane change).

The LDW+ system will be enabled and ready to provide feedback when the following conditions are met:

System voltage is in a normal operating range.
The vehicle ignition is in the ON/RUN state & driver has enabled the system & reverse gear is NOT engaged.
No LDW+ system faults are present.
Roads with positive or negative inclination transition (change in road grade) of up to 5%.
Left and Right lane boundaries are both detected simultaneously (HAPTIC only).
Vehicle speed is above 37 mph (60 km/h) and below 100 mph (180 km/h).
No intervention of the safety systems ABS, ESP and DAS Safety Requests, e.g. ABA, ACC takeover request, FCW, etc. Note: After the intervention of a safety system has ended, the LDW+ system can only provide haptic feedback warnings again after a calibrated period has been allowed to elapse.

The LDW+ system will retain the last system state (enabled or disabled) and the last lane warning sensitivity selected in the radio from the last ignition cycle when the ignition is changed to the On/Run position.

The system can be overridden by the driver using a variety of methods, including turn signals, driver steering torque, steering torque rate, and acceleration and deceleration rate. The LDW+ system can also be turned on or off with a single hard button on the switch bank. The LED on the button will inform the driver of the system status when the driver is not on the driver assist screen in the EVIC. The feature will automatically disable when a safety system engages (such as traction control).

The main component of the LDW+ system is the forward facing camera. The camera mounts near the rear view mirror and communicates on the CAN-C bus. The camera also has a dedicated private CAN B bus that connects directly to the radar sensor and that is used for forward collision warning and adaptive cruise control. The camera has the ability to detect alignment faults and is adjusted similar to the smart beam camera.

Another important factor in system operation is road condition. The forward facing camera has the ability to detect the contrast of the surface of the pavement and the white or yellow lines. Roads that are not marked or that have extremely worn markings may not be detected by the camera which will disable the system. While monitoring the EVIC display for driver assist systems, a customer can tell if the system is enabled by the solid lines on the display. This is also important for diagnosing an intermittent or inoperative concern.

The system also monitors the torque sensor inside the EPS to verify the driver's hands remain on the wheel. If no driver's steering input is received, the system will deactivate until all enabling conditions are met. These Include:

Drivers steering input.
The FFC can clearly detect the lines in the road.
There are no Diagnostic Trouble Codes (DTC) present in the steering or LDW+ system.
Vehicle speed is above 37 mph (60 km/h) and below 100 mph (180 km/h).

COMPONENT RESPONSIBILITY - BODY CONTROL MODULE (BCM)

Acquisition on the CAN-C bus of the LDW+ system enabled/disabled status from the Forward Facing Camera (FFC) to control the Auxiliary Switch Bank Module (ASBM) LED indication.
Acquisition on the CAN-C bus of the chime request from the FFC to inform the driver to place his/her hands on the steering wheel.
Acquisition on the CAN-C bus of the current LDW+ system sensitivity setting from the FFC.
Acquisition on the CAN-C bus of the current LDW+ system torque intensity setting from the FFC.
Acquisition on the LIN bus of the LDW+ system enable/disable switch (pressed/not pressed) status from the ASBM.
Gates the ASBM on/off signal command on LIN to a signal on CAN-C.
Gates the current ASBM status signal on CAN-C to the BCM concerning an ASBM control signal on the LIN bus.
Transmission on the CAN-B bus of the chime request to the Radio to inform the driver to place his/her hands on the steering wheel (audible alert).
Transmission on the CAN-B bus of the LDW+ system current sensitivity setting to the Radio.
Transmission on the CAN-B bus of the LDW+ system current torque intensity setting to the Radio.
Transmission on the CAN-C bus of the brake pedal status to the FFC.
Transmission on the CAN-C bus of the (left/right) turn signal lamp status to the FFC.
Transmission on the CAN-C bus of the wiper status (parked/not parked) to the FFC.
Transmission on the CAN-C bus of the LDW+ system enable/disable request to the FFC (gated from LIN).
Transmission on the CAN-C bus of the LDW+ system sensitivity setting request (gated from CAN-B) to the FFC.
Transmission on the CAN-C bus of the LDW+ system torque intensity setting request (gated from CAN-B) to the FFC.
Transmission on the LIN bus of the LDW+ system enable/disable switch indicator control status to the ASBM (gated from CAN-C).

COMPONENT RESPONSIBILITY - ELECTRONIC POWER STEERING (EPS)

Apply directional torque to the steering wheel based on lane position of vehicle during an unintentional lane departure.
Manage the Torque Overlay Interface (TOI).
Acquisition on the CAN-C bus of the torque overlay interface activation request from the FFC.
Acquisition on the CAN-C bus of the FFC system status from the FFC.
Acquisition on the CAN-C bus of the FFC drive style status from the FFC.
Transmission on the CAN-C bus of the steering angle and steering angle rate to the FFC.
Transmission on the CAN-C bus of the FFC Torque Overlay Interface activation status to the FFC.
Transmission on the CAN-C bus of the FFC Torque Overlay Interface fault status to the FFC.
Transmission on the CAN-C bus of the DST Torque Overlay Interface activation status to the FFC.
Transmission on the CAN-C bus of the EPS temporary deactivation status to the FFC.
Transmission on the CAN-C bus of the steering column torque to the FFC.
Transmission on the CAN-C bus of the steering column torque validity to the FFC.
Transmission on the CAN-C bus of the EPS motor torque to the FFC.
Transmission on the CAN-C bus of the EPS motor torque validity to the FFC.

COMPONENT RESPONSIBILITY - FORWARD FACING CAMERA (FFC)

Monitor the road scenario.
Process the video image.
Quantify the geometry of the lane boundaries in front of the vehicle.
Calculate the torque request to control the vehicle response based on lane position of vehicle.
Evaluate the "Hands Off" condition. When the driver's hands are not detected on the steering wheel, the system provides an audible warning consisting of left front and right front chimes to inform the driver to place his/her hands on the steering wheel.
Acquisition on the CAN-C bus of the EPS motor torque from the EPS.
Acquisition on the CAN-C bus of the FFC Torque Overlay Interface activation status from the EPS.
Acquisition on the CAN-C bus of the FFC Torque Overlay Interface fault status from the EPS.
Acquisition on the CAN-C bus of the effective torque applied on the steering wheel from the EPS.
Acquisition on the CAN-C bus of the brake pedal status from the BCM.
Acquisition on the CAN-C bus of the (left/right) turn signal request status from the SCCM.
Acquisition on the CAN-C bus of the (left/right) turn signal lamp status from the BCM.
Acquisition on the CAN-C bus of the wiper status (parked/not parked) from the BCM.
Acquisition on the CAN-C bus of the LDW+ system enable/disable request from the BCM.
Acquisition on the CAN-C bus of the customer-selected LDW+ system sensitivity setting from the BCM.
Acquisition on the CAN-C bus of the customer-selected LDW+ system torque intensity setting from the BCM.
Acquisition on the CAN-C bus of the ABS status from the BSM.
Acquisition on the CAN-C bus of the ESC status from the BSM.
Acquisition on the CAN-C bus of the DAS request active status from the BSM.
Acquisition on the CAN-C bus of the vehicle speed from the BSM.
Acquisition on the CAN-C bus of the yaw rate offset from the BSM.
Acquisition on the CAN-C bus of the lateral acceleration offset from the BSM.
Acquisition on the CAN-C bus of the longitudinal acceleration offset from the BSM.
Acquisition on the CAN-C bus of the ACC takeover request from the DASM.
Acquisition on the CAN-C bus of the Forward Collision Warning system status from the DASM.
Acquisition on the CAN-C bus of the engine start/stop status from the ECM.
Acquisition on the CAN-C bus of the gas pedal position from the ECM.
Acquisition on the CAN-C bus of the reverse gear status from the ECM.
Acquisition on the CAN-C bus of the steering angle from the EPS.
Acquisition on the CAN-C bus of the steering angle rate from the EPS.
Acquisition on the CAN-C bus of the DST Torque Overlay Interface activation status from the EPS.
Acquisition on the CAN-C bus of the EPS temporary deactivation status from the EPS.
Acquisition on the CAN-C bus of the yaw rate from the ORC.
Acquisition on the CAN-C bus of the lateral acceleration from the ORC.
Acquisition on the CAN-C bus of the longitudinal acceleration from the ORC.
Transmission on the CAN-C bus of the torque request to the EPS.
Transmission on the CAN-C bus of the LDW+ system enabled/disabled status to the BCM.
Transmission on the CAN-C bus of the chime request to the BCM (gateway) to inform the driver to place his/her hands on the steering wheel.
Transmission on the CAN-C bus of the current LDW+ system sensitivity and torque intensity settings to the BCM and IPC.
Transmission on the CAN-C bus of the LDW+ lane boundary detection status to the IPC.
Transmission on the CAN-C bus of the LDW+ warning status to the IPC.
Transmission on the CAN-C bus of the LDW+ ISO telltale status to the IPC.
Transmission on the CAN-C bus of the LDW+ display popup status to the IPC.
Transmission on the CAN-C bus of the LDW+ fault status to the IPC.

COMPONENT RESPONSIBILITY - INSTRUMENT PANEL CLUSTER (IPC)

Display LDW+ system state, configuration (sensitivity setting, torque intensity setting), lane boundary detection, warning and fault status.
Acquisition on the CAN-C bus of the LDW+ lane boundary detection status from the FFC.
Acquisition on the CAN-C bus of the LDW+ warning status from the FFC.
Acquisition on the CAN-C bus of the LDW+ fault status from the FFC.
Acquisition on the CAN-C bus of the LDW+ ISO telltale status from the FFC.
Acquisition on the CAN-C bus of the LDW+ display popup status from the FFC.
Acquisition on the CAN-C bus of the current LDW+ system sensitivity setting from the FFC.
Acquisition on the CAN-C bus of the current LDW+ system torque intensity setting from the FFC.

COMPONENT RESPONSIBILITY - AUXILIARY SWITCH BANK MODULE (ASBM)

Display LDW+ system defeat switch state (LED illuminated = LDW+ System is OFF, i.e. "defeated").
Transmission on the LIN bus of the LDW+ system enable/disable switch (pressed/not pressed) status to the BCM.
Acquisition on the LIN bus of the LDW+ system enable/disable switch indicator control status from the BCM.

CAMERA -

The camera is able to detect lane markings of any color (especially yellow and white which common colors for lane markings). The camera is able to detect and quantify the following information regarding the lane boundaries:

The lateral distance from the center of the vehicle to the left lane boundary.
The lateral distance from the center of the vehicle to the right lane boundary.
The heading angle of the vehicle with respect to the center axis of the lane.
A measurement of the radius of curvature of the road ahead of the vehicle.
The type of lane boundary, i.e. double line, solid line, dashed line, road edge.
The camera shall be capable of detecting if the camera lens is occluded and the windshield needs to be cleaned. During this condition, an indication is provided to clean the windshield.
The camera is capable of self-monitoring and diagnosis to determine whether it is operating properly.
The effective horizontal field of view of the camera is at a minimum of 36 degrees.
The effective vertical field of view of the camera is at a minimum of 20 degrees.

IMAGE ACQUISITION -

These functional requirements address a vision-based approach for measurement of vehicle lateral position relative to lane boundaries in the lane of travel.

In the daytime, the camera shall be able to detect lane markings where lighting and environmental conditions provide good visibility in excess of 30 meters.
At night, the camera shall be able to detect lane markings with lighting conditions provided by standard, production low beam headlamps, with or without additional sources of road illumination, and where environmental conditions provide good visibility in excess of 30 meters.
The camera shall be capable of compensating for sudden changes in lighting conditions such as during tunnel entry/exit.
The LDW+ system shall not have degraded performance from changes of the camera pitch angle due to vehicle dynamics (e.g. during hard braking or acceleration) or under maximum rated vehicle loading conditions, i.e. gross vehicle weight rating (GVWR).

The hard wired circuits between components related to the LDW+ system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the LDW+ system or the electronic controls and communication between ECU and other devices that provide some features of this system. The most reliable, efficient and accurate means to diagnose the LDW+ system and related communication operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.