LR3/Disco 3
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)
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. For additional information, refer to
Anti-Theft - Active
(419-01A Anti-Theft - Active)
Reverse lamps
Bayonet P21
21W
Cornering lamp/Static bending
lamp
Halogen H8
35W
NAS - Side marker lamp
(front/rear)
Capless W3W
3W
