Part 3
Exterior Lighting
ADAPTIVE FRONT LIGHTING SYSTEM (AFS)
The AFS is a system to improve driver visibility under differing driving conditions. AFS provides a larger visible area which is illuminated when cornering by adjusting the position of the beam distribution on the road. Horizontal adjustment is made automatically to the most suitable orientation for the driving conditions using steering angle and information from other vehicle sensors.
AFS is only available with adaptive Bi-Xenon headlamps. The 'Xenon' module within the headlamp is controlled by actuator motors which rotate the projector module on its horizontal axis to adjust the beam output to suit the cornering conditions and vehicle inclination. Only the adaptive bi-xenon lamp projector module swivels, the non adaptive xenon and halogen high beam lamp units remains static.
The AFS system is controlled by an AFS control module which is located at the bottom of the passenger side 'A' pillar. The control module controls the horizontal alignment of the adaptive Bi-Xenon projector module. The operation of the static bending lamp is controlled by the AFS control module, but powered by the CJB.
AFS Concept
AFS Control Module
The AFS control module is connected to the high speed CAN bus and receives inputs from other vehicle systems on the status of the following parameters:
- Steering angle - from steering angle sensor
- Vehicle speed - from ABS module
- Low beam status - from instrument cluster
- Suspension height - from air suspension control module
- Odometer value - for diagnostics only
- Engine running - from ECM
- Gear position - From transmission control module or transfer box control module
- Engine crank - from ECM
- Exterior/interior temperature - for diagnostics only.
The AFS will only operate when the AFS control module receives an engine running signal on the CAN bus. When the engine running signal is received, the AFS control module performs an initialization routine which is only performed at engine crank (power mode 9).
The AFS will also function when the lighting control switch is in the AUTO position and the AFS control module receives a lights on signal from the rain/light sensor and an engine running signal.
The AFS control module then monitors the inputs from the other vehicle systems to control the AFS functionality according to cornering angles and vehicle speed.
The AFS control module is connected to each headlamp on a private Local Interconnect Network (LIN) bus. The AFS control module then drives the DC motor actuators inside the headlamp assembly.
The AFS control module controls the swiveling angle of each projector module using speed and steering angle signals. The angles of each projector module differ to give the correct spread of light, For example, when turning left, the Left Hand (LH) projector module will have a greater swiveling angle than the Right Hand (RH) projector module
Reverse mode disables the swivel function when reverse gear is selected. The AFS projector modules move to their central straight ahead position and the static bending lamp, if active, will go off. When reverse gear is deselected, the AFS projector modules will move to a position to match the steering angle and the static bending lamp will illuminate if the operating conditions are correct (for example vehicle speed above 1.86 mph (3 km/h).
Xenon Headlamp Assembly with AFS Construction
The AFS xenon headlamp construction is similar to the non-AFS xenon headlamp assembly. The AFS assembly contains an additional carrier frame which provides the location for the AFS components. The remaining lamps are as described previously for the Xenon headlamp assembly. The functionality of the static bending lamp on the AFS headlamp is different from the functionality of the cornering lamp on the xenon headlamp.
The carrier frame has a radial bearing at the top and a thrust washer at the bottom which provide the horizontal pivot points for the xenon projector module. The lamp module lower pivot has a splined end which locates in the mating splines of the AFS horizontal actuator motor. The carrier frame is suspended on two flexible mountings at the top which provide for the vertical pivot points for the xenon projector module which allow for the vertical adjustment of the projector module. The bottom of the carrier frame is attached to the AFS vertical actuator motor.
The AFS actuator motors are dc motors which are driven by a power output from the CJB in response to signals from the AFS control module.
The actuators contain a potentiometer which is connected via wires with gold plated connector pins to the AFS control module. The two wires to each actuator provide a feedback signal to the AFS control module to give the precise position of the xenon projector module.
The AFS control module receives vehicle speed signals from the ABS module to adjust the projector module vertically to increase the beam range as the vehicle speed increases.
Initialization
When the AFS control module receives an engine running signal, the control module performs the initialization procedure which ensures that the headlamps are correctly aligned on their horizontal axis.
The AFS swivel initialization is completed in less than 1 second. The LH and RH AFS motors flick the headlamps to calibrate the centre position of the headlamps.
Failure Mode
In the event of a failure of the AFS system, a warning indicator in the instrument cluster is illuminated to warn the driver. The AFS warning indicator illuminates when the ignition is in accessory power mode 4 or ignition power mode 6 and will flash continuously until the fault is rectified. The AFS warning indicator will also be illuminated if a failure of the steering angle sensor or the vehicle speed signal is detected.
Illumination of the AFS warning indicator does not necessarily mean that there is a fault with the AFS system. The fault may be caused by a failure of another system preventing the AFS system operating correctly.
The AFS control module performs a diagnostic routine every time AFS is requested. If any fault is found, the AFS control module will suspend the operation of the AFS function.
If the AFS system has failed with the xenon projector module in a position other than the correct straight ahead position, the AFS control module will attempt to drive the xenon projector module to the zero (straight ahead) position. If this is not possible, the AFS control module will lower the projector module using the leveling actuator motors to prevent excess glare to oncoming vehicles.
The AFS control module software can detect an internal failure of the control module control circuits. The control module will power the projector modules to the zero position and prevent further operation.
Faults can be investigated by interrogating the AFS control module using an approved Land Rover diagnostic system to check for fault codes.
AUTOMATIC HEADLAMP OPERATION
The automatic headlamp function is a driver assistance system. The driver can override the system operation by selection of side lamp or headlamp on if the ambient light conditions require front and rear lighting to be active. The automatic headlamp system uses a light sensor and the CJB, which are connected via the LIN bus to control the headlamp functionality.
A light sensor is incorporated in the rain/light sensor located on the inside of the windshield, below the rear view mirror. The wiper system also uses the rain/light sensor for automatic wiper operation. For additional information, refer to Wipers and Washers The light sensor measures the ambient light around the vehicle in a vertical direction and also the angular light level from the front of the vehicle. The rain/light sensor uses vehicle speed signals, wiper switch position and the park position of the front wipers to control the system.
The automatic headlamp operation uses ambient light levels which are monitored by photodiode incorporated in the rain/light sensor. The rain/light sensor sends a lights on/off request to the CJB on the LIN bus, which responds by switching on the low beam headlamps, front side lamps and rear tail lamps.
The automatic headlamps are activated under the following conditions:
- Twilight
- Darkness
- Rain
- Snow
- Tunnels
- Underground or multistoried car parks.
Operation of the automatic headlamps requires the ignition to be in ignition mode 6, the lighting control switch to be in the 'AUTO' position and a lights on request signal from the light sensor.
HEADLAMP LEVELING
Headlamp leveling provides for the adjustment of the vertical aim of the headlamps. The leveling system is primarily required to minimize glare to other road users when a heavy load is in the rear of the vehicle.
Two systems of headlamp leveling are available; manual and static.
Manual Headlamp Leveling
Manual headlamp leveling is only available on vehicles with halogen headlamps and coil spring suspension.
The manual system comprises the following components:
- Two headlamp leveling motors
- Headlamp leveling rheostat rotary control.
When the ignition is in ignition mode 6, power is supplied to the lighting control switch via the ignition relay in the battery junction box and to the headlamp leveling motor in each headlamp assembly via the CJB. When the lighting control rotary switch is moved to the side lamp or headlamp position, the supply from the ignition relay is passed to the leveling rotary control.
Movement of the leveling rotary control produces a variable voltage output, which is sensed by the motors. The motors react to the supplied voltage and move the headlamp to the requested position which relates to the supplied voltage from the leveling rotary control.
The headlamps can only be lowered from their unladen position to compensate for changes in vehicle attitude due to loading.
Vehicle Headlamp Leveling
Vehicle headlamp leveling is only available on vehicles with air suspension.
Vehicle headlamp leveling is performed by the air suspension system and the air suspension control module. The suspension system constantly monitors the vehicle attitude and adjusts the height of the front and/or rear of the vehicle accordingly. This maintains the correct vehicle attitude and consequently maintains the correct headlamp beam alignment.
The vehicle leveling system is fully automatic, therefore the lighting control switch does not have the manual leveling rotary control.
HIGH BEAM ASSIST
High beam assist is a driving aid which automatically controls the high beam function. If required, the system can be overridden by the driver.
CAUTION: The high beam assist system is designed as a driving aid only. Should the road conditions require, it is the driver's responsibility to consider other road users and operate the high beam headlamps in a safe manner. In certain circumstances the driver will be required to intervene.
High Beam Assist Warning Indicator
The high beam assist system is controlled by a high beam assist control module which is located in the interior rear view mirror body and by the CJB. The module and the CJB are connected via the medium speed CAN bus.
The high beam assist control module receives a power supply from the CJB when the ignition is in power mode 6 (ignition on). The rear view mirror also includes a low resolution camera (image) sensor which detects headlamps and tail lamps of preceding vehicles. The sensor is connected to the control module which evaluates the image data, checking for light intensity and location.
If conditions are correct, the control module will activate the high beam assist by sending a high or low beam request message to the CJB via the medium speed CAN bus. The CJB then controls the shutter in the Xenon projector module together with the high beam fill-in lamp.
High Beam Assist Operation
The high beam assist operates as part of the automatic headlight system. When driving at night with the lighting control switch in the automatic position and the LH steering column multifunction switch in the central position, with sufficient darkness (approximately 1 lux or less) and a suitable road speed, the high beam assist will automatically operate the high beam lighting when necessary. A warning symbol in the instrument cluster confirms to the driver when the high beam assist system is selected and enabled.
NOTE:
The function of the normal 'blue' high beam indicator remains unchanged and it always reflects the actual status of the high beam lamps
NOTE:
The exterior lighting 'on' threshold for the auto headlamps system is approximately 100 lux which is measured by the rain/light sensor. At light levels below this value the low beam headlamps and exterior lights will be switched on. The high beam assist will not function until the light level has reached approximately 1 lux. At light levels above 1 lux high beam is not required and therefore is not activated.
Activation (system ready)
High beam assist will only activate and illuminate the warning indicator to show system is ready or 'primed' for high beam control, when the following conditions are met:
- High beam assist has been first 'enabled' via the instrument cluster menu
- Lighting control switch is in the 'Auto' position
- LH steering column multifunction switch in the central position
- The ambient light level is below 100 lux - refer to 'Light Levels' section that follows
- The system has not been overridden or cancelled - refer to 'Override' section that follows
- The camera (image) sensor view is not blocked.
High Beam Control
When activated, high beam assist will switch the headlamps to high beam when all the following conditions occur:
- No relevant oncoming traffic
- No relevant preceding traffic
- In non-urban environment, i.e. with no street lighting
- Ambient light level is below 1 lux - refer to 'Light Levels' section that follows
- Road speed is suitable - refer to 'Road Speed' section that follows.
Low Beam Control
When activated, high beam assist will switch the headlamps to low beam when any of the following conditions occur:
- Relevant Oncoming traffic is present
- Relevant Preceding traffic is present
- In urban environment, i.e. with street lighting
- Ambient light level is above 1 lux - refer to 'Light Levels' section that follows
- Road speed is not suitable - refer to 'Road Speed' section that follows
- Unrecognizable reflective inputs from road signs or markings - refer to 'System Limitations' section that follows.
Light Levels
The exterior lighting 'on' threshold for the normal 'auto headlamps' feature is approximately 100 lux and is measured by the windscreen mounted 'rain/light' sensor. When the light level falls to this value the low beam headlamps and exterior lights will be switched on together with the high beam assist warning indicator.
This warns the driver that the system is activated and ready to automatically switch on the high beam headlamps when the light level falls a little further to approximately 1 lux, as measured by the 'ambient light sensor' located in the mirror body. High beam is generally not required with light levels above 1 lux.
Road Speed
A road speed signal is received by the CJB from the Anti-lock Braking System (ABS) module via the high speed CAN bus. When the other activation conditions are correct, the CJB will switch the headlamps to high beam when the road speed has increased above 40 km/h (25 mph).
When the road speed falls to below 24 km/h (15mph), the CJB will switch the headlamps to low beam. The 10 mph (15 km/h) difference between the on and off road speed thresholds prevents the system continually switching between high and low beam at low speeds.
Override
The driver can manually override the high beam assist system at any time. When the high beam assist system is activated, pulling the LH steering column multifunction switch to the high beam 'flash' position or pushing it forward to the high beam position will de-activate the system and the high beam assist warning indicator in the instrument cluster will extinguish.
When the multifunction switch is returned to the central position, from a forward high beam position, the system is re-activated and the high beam assist warning indicator will illuminate again.
Correct Performance
In addition, high beam assist will only exhibit best performance if all of the following conditions are met:
- No false inputs are received by the camera (image) sensor, such as reflected light from certain static signs - refer to 'System Limitations' section that follows
- Headlamps are correctly aligned
- High beam assist system has been set for correct 'hand of traffic' via the driver menu settings - refer to 'Setting Hand of Traffic' section that follows
- Headlamps have been set for correct 'hand of traffic' via the mechanical tourist lever in headlamp casing - refer to 'Setting Hand of Traffic' section that follows
- Camera (image) sensor has been through a self learning 'auto aim' calibration procedure if any components have been replaced - refer to 'Calibration' section that follows
- There are no large reflective items, white papers, etc., sitting on top of the dash board in near view of the camera (image) sensor, or stickers placed directly in front of the camera (image) sensor
Driver Menu Features
The high beam assist feature must first be enabled using the configuration menu available in the instrument cluster. However if required, the high beam assist system can be permanently disabled leaving the basic 'Auto Lamps' system still operative.
Within this menu the system can also be configured for driving on the alternate side of the road (Hand of Traffic). This enables the system to be used in different regions and it's setting is important for correct operation.
Setting 'Hand of Traffic' and High Beam Assist 'Enable'
To set the high beam assist options the following steps must be sequenced:
- With the ignition in power mode 6 (ignition on), and the engine not running, use the controls on the steering wheel to select on the instrument cluster menu:
- Menu > Vehicle Set-up > High Beam Assist
- Configure the 'Hand of Traffic' setting by selecting the appropriate 'Drive on Left' (of road) or 'Drive on Right' (of road) to the applicable Market condition
- Enable the feature by setting 'Activate Assist' if not already selected.
NOTE:
Enabling or disabling high beam assist will not affect the 'Hand of Traffic' settings once set.
NOTE:
The headlamps still require manual adjustment using the tourist lever for driving abroad in countries where the alternate side of the road is used.
The instrument cluster menu also includes a 'High Beam Assist Sensitivity' selection. This is a requirement option for NAS market vehicles only but it is not recommended for normal use and has been superseded.
NOTE:
In other markets the 'Sensitivity' selection is grayed out and cannot be selected.
For additional information, refer to Instrument Cluster Description and Operation
System Limitations
The high beam assist system can occasionally have difficulty distinguishing between light from other vehicles or reflected light from static highly reflective road signs.
These situations may cause the high beam assist system to undesirably operate the high beam headlamps or take no action at all. Examples of these situations are as follows:
- Dips, hollows or crests in the road
- Highly reflective static Road signs
- Tight bends
- Poorly illuminated vehicles e.g. cyclists or small mopeds
- Motorway central barriers
- Extreme weather conditions e.g. Fog, heavy snow
- Exterior domestic or industrial lighting
Reflective Static Signs
Manual Deactivation
There are situations when a driver is able to judge if a high beam deactivation is desirable before the high beam assist system actually operates, for example over a crest of a hill. Headlamps from an oncoming vehicle can sometimes be seen on the horizon prior to the detection sensor receiving an input. It is the driver's preference to determine if early intervention is desired in this and similar situations.
System Diagnosis
NOTE:
Windshield stickers, stone chips, dirt and general road film will affect the successful operation of the image sensor if sufficient blocking is present. Avoid placing reflective objects on the instrument panel, for example white paper which can affect the image sensor.
High beam assist has a self diagnosis capability by comparing data from the ambient light sensor input (located in the rear view mirror) to light levels detected by the image sensor. If a deviation is detected it is assumed that the ambient light available to the image sensor is being restricted by dirt or other blockage and the system will be deactivated. Diagnostic Trouble Code (DTC)'s are stored in the control module's memory and can be accessed using an approved Land Rover diagnostic system. Within the diagnostic system is a procedure to test the basic operation of the camera function.
In the event of a fault, the warning strategy to the driver is as follows:
- Image sensor internal fault - green icon will extinguish with no additional message to driver
- CJB has lost all communication with image sensor - green icon will extinguish with no additional message to driver
- Image sensor blocked - green icon will extinguish with an additional "High Beam Assist Sensor Blocked" message within the message centre
System Calibration
To achieve effective operation of the high beam assist system, a calibration routine is performed on vehicle build and system tolerances are set to an accuracy of +/- 0.2 degrees.
This initial calibration is a 'one time only' procedure. Should the high beam assist components or the windshield require replacement at the dealership, an automatic calibration routine will be performed. This 'auto aim' calibration procedure is a continual process that takes place during a normal drive cycle at night and could take between 10 - 30 minutes dependant on the following driving conditions:
- If sufficient road markings (lane markings) are visible to the image sensor - approximately 10 minutes
- If insufficient road markings are visible, the system uses the tail lights of preceding vehicles - approximately 30 minutes.
NOTE:
Until this calibration is complete the system may not react correctly during operation. This should be made clear to the customer before vehicle handover. During any calibration or rectification work the headlamps should be checked for correct alignment.
NOTE:
Due to mechanical calibration tolerance the correct mirror assembly must be used for the vehicle model types in question and it is not exchangeable with other vehicle model types.
NOTE:
After any rectification work and before any calibration drives, the headlamps should be checked for correct alignment.
DAYTIME RUNNING LAMPS (DRL)
For additional information, refer to Daytime Running Lamps (DRL) Description and Operation