Land Rover Discovery: Battery, Mounting and Cables/ Description and Operation

COMPONENT LOCATION

1. Rear Junction Box (RJB)
2. Quiescent Current Control Module (QCCM)
3. Battery Monitoring System (BMS) control module
4. Primary battery
5. Gateway Module (GWM)
6. Central Junction Box (CJB)
7. Voltage Quality Module (VQM) - vehicles with auto stop/start system only
8. Starter motor or Tandem Solenoid Starter (TSS) motor on vehicles with auto stop/start system
9. Generator

OVERVIEW

The single primary battery is positioned on the left side of the engine compartment in a tray and is secured in position with a clamp plate and bolt assembly. The battery supplies electrical power to the starter motor, generator, Battery Junction Box (BJB), Central Junction Box (CJB) and Rear Junction Box (RJB).

The primary battery is an H7 80 Ah, 800 CCA Absorbed Glass Mat (AGM) Valve Regulated Lead-Acid (VRLA) battery on:

• TD4 2.0L Diesel engine vehicles
• All vehicles with auto stop/start system
• All vehicles with Fuel Fired Booster Heater (FFBH) with Cabin Heat Function.

The primary battery is an H7 80 Ah 700 CCA Flooded type battery on:

• TD4 2.2L Diesel engine vehicles without auto stop/start system
• GTDi 2.0L Petrol engine vehicles without auto stop/start system.

The primary battery is an H6 70Ahr 760CCA AGM Valve Regulated Lead- Acid (VRLA) battery on:

• TD4 2.2L Diesel engine vehicles with no fuel heater (temperate climates).

A Battery Monitoring System (BMS) control module is mounted on the primary battery negative terminal. The BMS control module is integral with the primary battery negative cable and is controlled by the Gateway Module (GWM).

CAUTION:

When connecting a slave power supply to the vehicle, to avoid damaging the BMS control module, always use the ground (negative (-)) terminal stud point on the right side top mount in the engine compartment. Never connect directly to the primary battery negative terminal when connecting a slave power supply to the vehicle, the BMS control module can be damaged.

The BJB is mounted adjacent the left front suspension top mount. The RJB is located on the left side of the luggage compartment behind the trim panel. The BJB and RJB contain fusible links, fuses, and relays to distribute electrical power to various vehicle systems.

NOTE:

The fusible links are mounted on the inboard side of the BJB behind removable covers.

The CJB is located behind the glovebox and receives its main power supply from the BJB. In addition to containing blade fuses, the CJB is the main controller for a number of vehicle systems. These functions are outlined in the relevant sections of this manual.

On vehicles with the auto stop/start system, the Voltage Quality Module (VQM) maintains the power supply of the several electrical systems during an auto stop/start engine start. This allows crucial vehicle systems to continue uninterrupted when there is a sudden draw of current from the primary battery. The VQM is located adjacent to the CJB.

TRANSIT MODE

All new vehicles will be delivered from the factory in transit mode. Transit mode replaces the traditional transit relay and inhibits a number of electrical systems and features to eliminate quiescent drain from the battery during delivery. Transit mode also inhibits some electrical loads when the engine is running to ensure that the battery is never discharged while the engine is running.

When the vehicle is in transit mode 'TRANSP' will be displayed in the Instrument Cluster (IC).

To remove the vehicle from transit mode, the Land Rover approved diagnostic system must be connected during the Pre-Delivery Inspection (PDI). For more information, refer to the PDI manual.

POWER MODES

The CJB (Central Junction Box) controls the power supplies for the various vehicle functions. There are 9 power modes available which are used by various systems to determine the operating condition of the vehicle. Only five of these modes will be noticeable to the driver and technicians as follows:

• Power mode 0 - Ignition off
• Power mode 4 - Accessory
• Power mode 6 - Ignition
• Power mode 7 - Engine running
• Power mode 9 - Crank.

DESCRIPTION

BATTERY MONITORING SYSTEM (BMS) CONTROL MODULE

A Battery Monitoring System (BMS) control module is located on the primary battery negative (-) terminal and is clamped to the terminal with a bolt and nut.

The primary battery negative ground cable is connected to the BMS control module and is attached to a ground stud on the vehicle body.

The BMS control module is connected into the vehicle wiring harness via a multiplug. The BMS control module receives a 12V power supply direct from the primary battery positive terminal. A Local Interconnect Network (LIN) bus connection provides communication between the BMS control module, the Gateway Module (GWM) and the Quiescent Current Control Module (QCCM) for control and monitoring of the primary battery current drain and state of charge.

The BMS control module measures the primary battery current and voltage, which it communicates to the GWM over the LIN bus connection. The GWM also receives generator output information on a LIN bus connection. The GWM transmits the primary battery and generator information over the High Speed (HS) Controller Area Network (CAN) powertrain and chassis system busses and the Medium Speed (MS) CAN body and comfort system busses to other vehicle systems. Based on the information received from the BMS control module, the GWM and the Engine Control Module (ECM) will control the output from the generator and request the switching off of electrical loads if necessary.

CAUTION:

Due to the self-calibration routine, it is recommended that all power supply diagnostic testing is carried out using the Land Rover approved diagnostic system rather than a digital multimeter.

The BMS control module is able to generate Diagnostic Trouble Codes (DTC)s to help diagnose BMS related issues. These DTCs can be read using the Land Rover approved diagnostic system. The Land Rover approved diagnostic system can also be used to implement a primary battery and generator self-test routine.

For additional information, refer to: Battery (414-01 Battery, Mounting and Cables, Diagnosis and Testing).

If a fault is detected, the GWM and the ECM will override the BMS control module.

The BMS control module DTC's can be used to help diagnose BMS hardware or communication faults. The DTC's are stored in GWM. The Land Rover approved diagnostic system has a process for an automated power supply diagnostic procedure. The procedure provides a menu driven process to locate a fault in a logical sequence. The procedure uses the capability of the BMS control module and generator LIN bus controlled functions to provide current flow information and will detect if the BMS control module or generator is not functioning correctly.

BMS Low Battery Warning and Energy Management Messages

The BMS continuously monitors the condition of the primary battery. If excessive battery discharge occurs, the system will begin to shut down nonessential electrical systems in order to protect the primary battery.

If the BMS calculates that primary battery condition is not within set parameters, there are 3 messages that can be displayed; two on the Touch Screen (TS) and one on the Instrument Cluster (IC) message center. These inform the user that the primary battery is either at a low level of charge or the engine-off power consumption limit has been exceeded.

• Low Battery - Please switch engine on or system will shutdown in 3 minutes: is displayed as a warning on the TS if the engine is not running.

  This indicates that the primary battery charge has fallen below a predefined threshold. As soon as the primary battery is charged above this threshold, the message will be removed.

• Low Battery - Please start your engine: is displayed on the IC message center if the engine is not running. This indicates that the primary battery charge has fallen below a predefined threshold. As soon as the battery is charged above this threshold, the message will be removed or it can be manually removed by pressing the 'OK switch on the steering wheel switchpack'.
• System will shut down in 3 minutes: is displayed as an energy management on the TS if the engine is not running, and system features are causing excessive primary battery discharge. After 3 minutes the BMS will begin shutting down vehicle systems. Normal system operation will resume when the engine is started.

This is based on a percentage of primary battery capacity available for the customer to use with the engine off. The percentage can change based upon several factors.

Once activated, the resetting of this message will not occur until the vehicle is driven for 10 minutes with the engine running (to allow the primary battery to replace any lost charge). However, if the engine is run for less than 10 minutes, the message will only be displayed after an additional 5 minutes with the ignition on (power mode 6) but the engine off.

VOLTAGE QUALITY MODULE (VQM) - VEHICLES WITH AUTO STOP/START SYSTEM ONLY

A Voltage Quality Module (VQM) is fitted to vehicles with the auto stop/start system. The VQM is located adjacent to the CJB, behind the glovebox. During an auto stop/start engine start cycle the VQM maintains some of the vehicle's electrical systems by supplying a support voltage around the vehicle's electronic components during an engine restart. This allows crucial vehicle systems to continue uninterrupted when there is a sudden draw of current from the primary battery.

QUIESCENT CURRENT CONTROL MODULE (QCCM)

The Quiescent Current Control Module (QCCM) is located in the rear left of the luggage compartment, behind the trim panel.

An addition to the Battery Monitoring System (BMS), and using signals already transmitted by the BMS control module, the QCCM cuts the power supply to other non-essential control modules to avoid excessive discharge of the primary battery. The power supplies are cut by opening the contacts of relays integral with the QCCM. The systems supplied via the QCCM are the audio/entertainment systems and the climate control systems.

Some control modules can cause unnecessary primary battery drain due to the control module staying awake after the vehicle electrical system has been shut down. The QCCM in conjunction with the Gateway Module (GWM), monitor and control the systems to prevent primary battery discharge.

The system comprises three components:

• BMS control module
• GWM
• QCCM.

The battery monitoring system checks primary battery health by analyzing battery quiescent current, battery current drain or state of charge, and determines if any action is required to protect the primary battery. If action is required this is communicated to the GWM.

The GWM software uses this information to determine if action is required to assist primary battery protection. The QCCM receives relay open and close commands from the GWM and reacts accordingly.

The software that controls the QCCM is contained within the GWM.

The system will be set in transit mode on delivery. Transit mode has no QCCM operation and the relays remain closed. Therefore primary battery drain could occur and the system will not react to it.

A Pre-Delivery Inspection (PDI) process requires the system to be taken out of transit mode and put into normal mode, which enables the QCCM, before handing over to the customer.

The QCCM has a routine to clean the integral relay contacts if required. This routine is performed using the Land Rover approved diagnostic system and, if unsuccessful, the QCCM will require replacement.

The QCCM contains a number of fuses which supply and protect the audio/entertainment systems, the climate systems, and the GWM.

GATEWAY MODULE (GWM)

The GWM is attached to a bracket, which is attached to the passenger side of the instrument panel cross-car beam, behind the instrument panel.

The GWM contains software to control the following functions:

• Determine the condition of primary battery
• Control the output from the generator using load management software
• Controls the auto stop/start system using power management to inhibit unnecessary electrical loads.

The GWM communicates with other system control modules on the High Speed (HS) CAN powertrain and chassis systems busses and the Medium Speed (MS) CAN body and comfort systems busses.

The GWM communicates with the BMS control module, the QCCM, and the generator via a LIN bus.

PRIMARY BATTERY STARTER MOTOR FUSE

A fuse to protect the starter motor and generator is located in the power cable from the primary battery positive terminal to the starter motor and generator.

The fuse is integral to the cable and cannot be replaced separately. In the event of fuse failure, the cable assembly must be replaced.

OPERATION

BATTERY MONITORING SYSTEM (BMS)

When the ignition is off (power mode 0), the BMS control module records the primary battery state of charge and begins to monitor the battery condition from this point.

If the primary battery state of charge falls by 7%, the BMS control module will monitor the primary battery for 5 minutes. The BMS control module sends a 'warning' message on the LIN bus to the GWM. If after the 5 minute monitoring period, the primary battery charge has continued to fall or is below 50% due to the quiescent drain current being too high, the BMS control module will determine that some control modules are still 'awake'.

The BMS control module sends a shutdown message on the LIN bus to the GWM. The GWM sends a CAN bus message on the Medium Speed (MS) CAN body and comfort systems bus, and High Speed (HS) CAN powertrain and chassis systems bus to all control modules, requesting them to shutdown.

The BMS control module will monitor the primary battery state of charge for a further 15 minutes and determine if the battery state of charge is still dropping.

The BMS control module sends a 'Power Disconnect' signal to the GWM on the LIN bus. The GWM then sends a signal to the Quiescent Current Control Module (QCCM) on the LIN bus to open its internal relays. When the QCCM relays are open, the power supply from the primary battery to non-critical control modules is removed. The non-critical control modules are any modules associated with the audio/infotainment system and also the climate control system.

The use of a LIN bus communication ensures that no other control modules are 'woken' during this process. If CAN bus communication was used, all modules on the CAN bus would be woken by the message.

BMS CONTROL MODULE SELF CALIBRATION

Periodically the BMS control module will initiate a self-calibration routine.

Before making the self-calibration, the battery monitoring system first charges the primary battery to its full condition.

NOTE:

If the vehicle is only driven for short periods the charging process could take a number of days to complete.

Once the primary battery is fully charged, the BMS control module will discharge the primary battery to approximately 75% of its full state of charge, but never lower than 12.2 V. The time taken to complete this part of the routine is dependent on the electrical load on the vehicle.

When the second part of the routine has been successfully completed, the BMS control module will return the primary battery to its optimum level of charge. The optimum level of charge will be between 12.6 V and 15 V, depending on primary battery condition, temperature and loading.

The BMS control module also monitors the primary battery condition with the engine switched off. If a low voltage condition is detected the BMS control module can request the infotainment system to switch off to protect battery voltage.

CONTROL DIAGRAM

NOTE:

A = Hardwired; D = High speed CAN powertrain systems; O = LIN bus

1. Gateway Module (GWM)
2. Engine Control Module (ECM)
3. High Speed (HS) CAN powertrain system bus to other system control modules
4. Generator
5. Ground
6. Fused power supply from Central Junction Box (CJB)
7. Battery Monitoring System (BMS) control module

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