Communication network of modules (Freelander 2)

The vehicle's electrical wiring system contains several different types of communication networks that serve to transmit commands and information between control modules. The configuration on a specific vehicle depends on the model and the trim level.

On-board communication networks are:

• LIN bus (Local Interconnect Network)
• Medium speed CAN bus
• High-speed CAN bus
• Contour Media Oriented System Transport (MOST)

Tire	Data transfer rate
LIN bus	9.6 kbps
Medium speed CAN bus	125 kbps
High-speed CAN bus	500 kbps
MOST circuit	24 Mbps.

LIN bus

LIN bus (Local Interconnect Network) - is a low-speed broadcast network that consists of master and slave (worker) elements. The master element transmits a message over a single wire to the slaves, identifying which slave should respond. The message has a header (the worker identifier) and an empty data field. The identified slave fills the data field with the appropriate information and returns the message to the master element over the same wire.

CAN bus

CAN bus (Controller Area Network) – is a high-speed data line over which control modules automatically transmit information every few microseconds. The information is transmitted over a pair of twisted wires known as CAN high and CAN low. The information is transmitted over the CAN bus as the voltage difference between the two wires.

There are two CAN networks used on the vehicle - medium speed and high speed - and the CJB acts as a gateway between the two networks. The table below shows the wire colours used on both networks.

Net	High	Low
Medium speed tire	Grey and orange	Purple and orange
High speed tire	White and blue	White

MOST circuit

MOST circuit (Media Orientated System Transport) uses optical fibre cables to transmit data and audio signals related to the infotainment system. The optical fibre cables are arranged in a loop, and each loop block has 'MOST in' and 'MOST out' connectors.

The MOST circuit is a synchronized network. The master device of the network sets the time, and all other devices in the circuit operate according to the synchronizing pulses of this timer. The synchronizing unit for the MOST circuit is the integrated control module.

When performing maintenance work on MOST fiber optic buses, the following precautions must be observed:

• After disconnecting any wires, carefully install the appropriate dust caps to protect the mating surfaces of the connectors from damage or contamination.
• Do not bend the fiber optic cables with a bending radius less than 25 mm or twist them when performing maintenance or repair. Sharp bending or twisting may degrade performance, cause immediate system failure or future failure.
• Avoid applying excessive force and causing deformation or stress to the fiber optic cable or connectors, especially residual stress after installation.

Diagnostics using a checkpoint

The additional junction box (AJB) has an RBD link built into it (Ring Break Diagnostics). The RBD link contains a copper jumper that, when removed, initiates the test point diagnostic mode. The test point diagnostic mode allows a mechanic to locate a break in the MOST loop fiber. To initiate the test point diagnostic mode, perform the following procedure:



(Data taken from the website: www.lrman.ru)

• Connect Land Rover approved diagnostic equipment.
• Set the vehicle to power mode 4 or higher.
• Remove the RBD jumper within the time period specified by the Land Rover approved diagnostic system.
• Replace the RBD jumper.

After approximately 30 seconds, a diagnostic trouble code (DTC) will be stored in the integrated control module identifying the location of the fault. The DTC is read using the Land Rover approved diagnostic system.