Part 1

Exterior Lighting

Exterior Lighting Component Location









OVERVIEW
The exterior lighting is controlled by the Central Junction Box (CJB). The CJB controls the following vehicle functions:
- Control and monitoring of exterior lamps including turn signal indicators and hazard warning functionality
- Illumination dimmer control of instrument cluster and all interior switch illumination
- Communication and control and monitoring of trailer lighting via the trailer module
- Monitoring and evaluation of check control inputs from other system control modules and output of applicable messages in the instrument cluster message center.
The CJB is connected to the medium speed Controller Area Network (CAN) bus and communicates with other vehicle systems via the instrument cluster. The CJB contains a microprocessor which performs the control, monitoring and evaluation functions.
A combined rain/light sensor is fitted which controls the automatic wiper operation and the automatic lighting function.
An Auto High Beam system can also be fitted which automatically controls the high beam headlamps.
The exterior lighting system comprises the following exterior lamps:
- Front and rear side lamps
- License plate lamps
- Side marker lamps (if fitted)
- Front and rear turn signal indicator lamps
- Turn signal indicators side repeater lamps
- Stop lamps and high mounted stop lamp
- Reversing lamps
- Rear fog lamps
- Front fog lamps
- Static bending lamps (if fitted - AFS headlamp except NAS)
- Low and high beam headlamps
- Adaptive Front lighting System (AFS) (if fitted).

Exterior Lamp Bulbs
The following table shows the bulbs used for the exterior lighting system and their type and specification.





The bulbs and the Light Emitting Diode (LED)'s are driven by Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) within the Central Electronics Module (CEM) which is an integral component of the CJB. An exception to this is the rear tail lamps, front fog lamps and reverse lamps which are supplied with power via relays within the CJB and are protected by conventional fuses.

CENTRAL JUNCTION BOX
The CJB is located behind the glove compartment and is connected to the vehicle wiring harness with 8 multiplugs.
The CJB receives four permanent battery power supplies via the Battery Junction Box (BJB).
The lighting circuits are not all protected by conventional fuses as some are protected by Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). The control circuitry within the CJB and the CJB for each individual circuit can detect and isolate a problem circuit.
Failure of a lamp is not notified to the driver. If a turn signal indicator fails the turn signal warning indicator in the instrument cluster will flash at double speed.

Input Signals for Lamp Control
The CJB receives inputs from the following switches:
- Lighting control switch for side lamps, headlamps and auto headlamps
- Momentary push switches for front and rear fog lamps
- Left hand steering column multifunction switch for turn signal indicators and high beam/headlamp flash and Auto High Beam system
- Brake pedal switch
- Momentary push switch for hazard warning.
The switches are supplied with a 10mA supply from the CJB and switch to ground when operated. The CJB detects that a switch has been operated (ON) when its closing resistance is less than 100 Ohm and is detected as OFF when its resistance is more than 10K Ohm.
The lighting control switch uses a binary system which is detected by the CJB which determines the selected position. The output from the lighting control switch is shown in the following table:





The CJB also receives ignition status via hard wired connections from the stop/start switch.
A reverse gear engaged signal is also received on the high speed CAN bus from the Transmission Control Module (TCM) to enable the CJB to activate the reverse lamps.
The CJB can receive a hazard warning indicator activation message from the Restraints Control Module (RCM), via the high speed CAN bus, in the event of a crash. The CJB can also activate the hazard warning indicators to signify vehicle locking to the driver.
On vehicles with Auto High Beam, the auto high beam control module outputs signals on the medium speed CAN bus to the CJB to control the high beam headlamps.

Circuit Protection
Operation of the lamps is performed using overload proof Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). The MOSFETs can detect overload, load interruption with the lamps switched on and short circuit to positive with the lamps switched off.
The MOSFETs are protected against short circuits, removing the requirement for the lamps circuits to be protected by fuses. The MOSFETs respond to heat generated by increased current flow caused by a short circuit. Normally this would cause the fuse to blow. The MOSFETs react to the heat increase and cut the supply to the affected circuit. Once the fault has been rectified or the MOSFET has cooled, the MOSFET will automatically reset and operate the circuit normally.
If an overload occurs, the current flow is dependant on the temperature of the related MOSFET and can be up to 20 times the rated current of the lamp. The MOSFET heats up and deactivates the load applied to the circuit. When the MOSFET cools the circuit is once again reactivated. This thermal cycling occurs continuously in the event of an overload occurring.
A number of lamps are controlled by relays and these circuits are protected by conventional fuses.

Bulb Monitoring
Bulb failure monitoring is performed by the CJB processor. The lamps are cold and warm monitored by the MOSFETs in order to detect bulb failure.

NOTE:
Relay controlled lamps have no diagnostic monitoring.
The CJB processor provides outputs to each MOSFET. The output switches the MOSFET to supply the required output to power the applicable lighting circuit. The microprocessor evaluates the circuits by detecting the returned signals from the controlling MOSFET.
When the bulb or LED is functioning normally, the output signal voltage from the controlling MOSFET is 0V. If a bulb or LED in the circuit fails, an open circuit occurs and the MOSFET outputs a signal of 5V to the processor. The signal is interpreted as a bulb or LED failure and generates a Diagnostic Trouble Code (DTC) which can be retrieved using an approved Land Rover diagnostic system.
Warm monitoring is performed continuously when the lights are switched on by evaluating the diagnostic output of the MOSFET switches. Cold monitoring is performed at 32 second intervals when the lights are switched off. The MOSFETs briefly switch on the lights for approximately 1 millisecond (this is insufficient to illuminate the bulb or LED) and checks the bulb or LED as per warm monitoring.
Cold monitoring is not possible for the low/high beam headlamps of vehicles using xenon bulbs. On these vehicles the cold monitoring of the low/high beam headlamps is switched off in the CJB. The CJB detects a failed xenon bulb via a reduction in current flow to the affected headlamp's xenon control module.
When a xenon bulb fails, the control module's current consumption falls to 60mA, which the CJB detects as unsuccessful bulb illumination.

Alarm Indications
The CJB can also display alarm visual indications for alarm arm, disarm and triggered conditions.
If the hazard warning lamps are active when a lock or unlock request is made, the hazard warning cycle is interrupted to allow the visual indication of the requested lock cycle. When visual indication is completed, the hazard warning operation will continue.
If the vehicle is involved in crash of a severity for the RCM to initiate deployment of the airbags, the control module outputs a hazard warning lamps on request on the medium speed CAN bus to the CJB. The hazard warning lamps will be activated and will continue until the RCM outputs a message to deactivate the hazard warning lamps.

Redundant Data Storage
The CJB stores data relating to the Vehicle Identification Number (VIN), total mileage and service interval indicator. This data is received by the CJB from the instrument cluster and used as a back-up in the event of instrument cluster replacement.
If the CJB is to be replaced, an approved Land Rover diagnostic system must be connected to the vehicle and the CJB replacement procedure followed to ensure that the stored data is transferred to the new unit.

Low Voltage Operation
If the battery voltage falls below 11.2V, the CJB operates the minimum lighting to preserve the remaining battery charge.

Crash Signal Activation
In the event of an accident of a severity to activate and deploy the airbags, the Restraints Control Module (RCM) requests various electrical operations to assist with the crash situation. The RCM requests via the bus systems to the CJB to activate the hazard warning lamps.

Security System Activation
In the event of the security system being triggered, the CJB requests activation of the hazard warning lamps.

Instrument Panel and Switch Illumination Dimming
The CJB controls the instrument cluster backlighting illumination and also illumination of all instrument panel switches.
The CJB supplies a power output to all switch illumination bulbs at a voltage determined by the position of the manual dimmer rheostat. The switch illumination is activated when the lighting control switch is in the side lamp or headlamp position.

DIAGNOSTICS









The diagnostic socket allows for the transfer of information between the CJB and the approved Land Rover diagnostic system. The diagnostic socket is located in the lower instrument panel, above the pedals. The socket is secured in the instrument panel and protected by a hinged cover.
The CJB has diagnostic capabilities and stores fault codes relating to the lighting systems. The xenon control modules cannot be interrogated via the CJB.

LIGHTING CONTROL SWITCH









The lighting control switch is located in the instrument panel between the steering column and the driver's door. The switch comprises a four position rotary switch for controlling side lamps and headlamps, a thumbwheel rheostat which manually controls the instrument panel and interior switch night illumination, and momentary push switches for front and rear fog lamps.
The rotary side and headlamp control switch has 2 connections to the CJB. These 2 connections supply a hardwired binary code to the CJB which correspond to the switch position selection made.
The front and rear fog lamp switches operate by completing earth paths for a reference voltage from the CJB when the switch is pressed. The fog lamp switches are momentary, non-latching switches which briefly complete an earth path which is sensed by the CJB.

Lighting Control Switch Illumination
When the stop/start switch is pressed to activate the accessory or ignition power modes, the switch legends on the lighting control switch are illuminated at maximum brightness when the lighting control switch is in the 'O' (off) position. When the lighting control switch is rotated to the side, headlamp or AUTO position the legend illumination is dimmed.

HEADLAMP ASSEMBLY

General
Two types of headlamp are available; Bi-xenon or Adaptive Front lighting System (AFS).
The headlamps are located on the bonnet locking platform. Each headlamp is secured at the top to the bonnet locking platform with 1 screw, 1 screw at the bottom to the front bumper support bracket, 1 screw on the fender edge bracket and 1 screw on the headlamp mounting panel. Headlamp removal is facilitated by removal of the radiator grille, front bumper and removal of the 4 headlamp attachment screws.
Headlamp removal is not required for replacement of the xenon or halogen bulbs. The rear of the headlamp unit has removable access covers which allow access to the bulbs and tourist lever.
A large cover, which is rotated counter-clockwise to remove, allows access to the low/high beam xenon bulb.
A second cover, on the inboard side of the headlamp, can be removed to allow access to the high beam 'fill-in' lamp halogen bulb. The bulb is mounted in a holder with an extended end to aid removal.
The turn signal indicators, side lamps, static bending lamp (where fitted) and the side marker lamp (where fitted) are LED's. None of the LED's are serviceable items.
In all markets except NAS, the headlamps have two adjustment screws which allow for the manual setting of the vertical and horizontal beam alignment. A 6mm Allen key is used to rotate the adjusters to achieve the required setting. The inboard adjuster controls the vertical aiming and the outboard adjuster controls the horizontal aiming.
On NAS vehicles the headlamp is regarded as 'Visual Optically Left' (VOL) aiming. There is no horizontal adjustment. Refer to the Service Repair Procedures manual for headlamp alignment data and procedures.
Each headlamp has an integral sixteen pin connector which provides inputs and outputs for the various functions of the headlamp assembly. The usage of the pins differs between model variants. Refer to the Electrical Library and circuit diagrams for pin details.
Two breathers are located on the rear of the headlamp housing. The Goretex breathers allow air flow in and out of the headlamp but prevent the ingress of moisture from rain, road spray or washing. If condensation occurs within the headlamp, check that the breathers are not blocked with mud etc before further action is taken.