Battery And Cables (G1950059): Overview: Notes

The primary battery provides power to the Battery Junction Box (BJB) which delivering power to the:

Body Control Module/Gateway Module (BCM/GWM) assembly
Passenger Junction Box (PJB)
Engine Junction Box (EJB)
Rear Junction Box (RJB)
Auxiliary Junction Box (AJB)
Voltage Quality Module (VQM) - Single battery system with auto stop/start system only - All vehicles, except cold climate TDV6 3.0L diesel engine and TDV8 4.4L diesel engine vehicles
Power Supply Distribution Box (PSDB) - Dual battery system only - TDV8 4.4L diesel engine and cold climate TDV6 3.0L diesel engine vehicles
Jump start terminal - Positive
Starter motor and generator.

The junction boxes contain fusible links, fuses, and relays to distribute electrical power to various vehicle systems.

A Battery Monitoring System (BMS) sensor is mounted on the primary battery negative terminal. The BMS sensor is integral with the primary battery ground cable and is controlled by the BCM/GWM assembly.

The auxiliary battery is not equipped with a BMS sensor.

CAUTION: When connecting a slave power supply to the vehicle, always use the ground terminal stud point on the right side top mount in the engine compartment. Never connect directly to the battery negative terminal, because the BMS sensor can be damaged.

If a new primary battery is fitted to the vehicle, the BMS sensor will require re-calibrating using a Land Rover approved diagnostic equipment. This will also apply if a new auxiliary battery is fitted to TDV8 4.4L diesel and TDV6 3.0L diesel cold climate vehicles.

The BCM/GWM assembly is the main controller of the vehicle body systems. The BCM/GWM assembly contains most of the software required to control the battery charging system and components. The BCM/GWM assembly monitors the components and can store fault related Diagnostic Trouble Codes (DTCs).

The dual battery system is used on TDV8 4.4L diesel engine and TDV6 3.0L diesel engine vehicles in cold climate markets with or without stop/start system. The dual battery system prevents the vehicle electrical systems from being subjected to undesirably low voltages during repeated engine restarts. If the electrical systems are subject to low voltages the user may notice degraded performance of components and systems. In this case incorrect fault Diagnostic Trouble Codes (DTCs) may be stored.

The dual battery system switches the auxiliary battery in parallel with the primary battery if:

The ambient temperature falls below a certain threshold
The state of charge of the primary battery falls below a certain level.

Thereby the auxiliary battery is able to assist the primary battery in cranking the car at a suitable speed to provide a start.

Monitoring of the primary and auxiliary battery condition is controlled by the BCM/GWM assembly and the BMS sensor.