Central Junction Box

CENTRAL JUNCTION BOX

The Central Junction Box (CJB) is an integrated unit located behind the fascia on the passenger side of the bulkhead. The CJB contains fuses, relays and a number of microprocessors which control the power supply and functionality of the lighting system and other vehicle systems.

Input Signals
The CJB receives inputs from the following switches:
^ Lighting control switch
^ Side lamp position
^ Headlamp position
^ Automatic (AUTO) position (if fitted)
^ Brake switch
^ Left hand steering column multifunction switch for turn signal indicators and high beam/headlamp flash
^ Hazard flasher switch
^ Rain/light sensor (LIN signal)

Circuit Protection
The CJB provides circuit protection for all exterior lighting circuits. Most exterior lighting circuits are protected by conventional fuses, however, the following circuits are protected by Field Effect Transistors (FETs).
^ Low beam
^ High beam
^ Cornering/static bending lamps
^ Turn signal lamps
^ Trailer turn signal lamps.

Operation of the above listed circuits is protected by FETs which can detect overloads and short circuits. The FETs respond to heat generated by increased current flow caused by a short circuit. On a normal circuit this would cause the fuse to blow. The FETs respond to the heat increase and disconnect the supply to the affected circuit. When the fault is rectified or the FET has cooled, the FET will reset and operate the circuit normally. If the fault persists the FET will cycle, disconnecting and reconnecting the power supply.

The CJB stores fault codes which can be retrieved using T4. The fault code will identify that there is fault on a particular output which will assist with fault detection.

Alarm Indications
The exterior lighting system is used for alarm arm and disarm requests.

When the driver locks the vehicle, a visual indication of a successful lock request is displayed to the driver by the hazard flashers operating three times with a pattern of 500ms on and 500ms off.

When the driver unlocks the vehicle, a visual indication of a successful unlock request is displayed to the driver by the hazard flashers operating once for 3 seconds.

If the alarm is triggered, the hazard flashers are operated for ten 30 second cycles of on for 380ms and off 380ms with a 5 second off delay between each cycle.

Lights on Warning Chime
When the ignition switch is in the off (0) or auxiliary (I) position and the lighting control switch is in the side lamp or headlamp position, a warning chime will sound if the driver's door is opened. This indicates to the driver that the exterior lights have been left on.

The chime is generated from the instrument cluster sounder on receipt of a lights on signal, a door open signal and an ignition switch off signal from the CJB on the CAN bus.

Crash Signal Activation
When a crash signal is transmitted from the restraints control module, the CJB activates the hazard flashers and the turn signal indicators in the instrument cluster.

The hazard flashers will continue to operate until the ignition switch is moved to the auxiliary position I or the position O or the restraints control module no longer transmits the crash signal.

Headlamp Timer
The CJB controls a headlamp timer function which allows the headlamps to remain on for a period of time after leaving the vehicle. This is a driver convenience feature which illuminates the driveway after leaving the vehicle.

To select this feature, the lighting control switch must be in the headlamp or side lamp position when the ignition switch is moved from the ignition position to off. The lighting control switch must be moved to the off position or AUTO position (if fitted) to activate the timer. The timer function will then be initiated and low headlamps will be illuminated for the selected timer period.

The timer period is selectable by the driver and can range from off to 60 seconds in 10 second increments. The default timer period is set at 20 seconds.

The default setting can be changed by a Land Rover or authorised dealer or by the driver using the vehicle's customer personalisation options.

With the vehicle stationary and the ignition switch in any position, pressing the trip computer button on the end of the left hand steering column multifunction switch gives access to the options. The options can be scrolled through using the audio search buttons on the steering wheel. The options are displayed in the message center. When the headlamp timer option is reached, the settings can be changed using the audio search buttons on the steering wheel. When the selection has been made confirmation is performed by pressing the trip computer button.

NOTE: The headlamp timer feature will be cancelled under the following conditions:

The headlamp timer can also be operated using the ignition key personal button, if this feature has been set by the driver.