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Battery: Description and Operation





Battery and Cables

COMPONENT LOCATION









INTRODUCTION
Electrical power from the battery and generator is distributed throughout the vehicle through a series of junction boxes.

IGNITION MODES
The vehicle has a possible four ignition modes. The modes and systems that are active in each mode are detailed in the following table:





BATTERY





The battery is located behind a cover at the front of the luggage compartment. The cover is held in place by four retainers. The battery sits in a tray and is secured with a clamp plate and two nuts.
The positive and negative battery cables are fitted with service loops. The service loops add extra length to the cables and allow the battery to be slid rearward in the luggage compartment without disconnection.

Remote Jump Start Terminal
The positive battery cable is also connected to a remote jump start terminal. The remote jump start terminal is located in the LH (left-hand) rear corner of the luggage compartment and can be accessed by removing the air vent trim. Although also fitted to coupe vehicles, the terminal has been specifically designed to allow a convertible vehicle to be jump started if a drained battery is experienced when the top is in the stowed condition.
The starter motor power lead is also connected to the remote jump start terminal and is insulated from the battery jump start cable and the vehicle body by a nylon washer.
The negative jump start connection is a stud located in the spare wheel well. For more information on jump start procedure, refer to the Owner's Handbook.

Transit Relay
The vehicle is also fitted with a transit relay. This is a disposable device and not for use by the customer. This relay is fitted in series with the battery and ground. It disconnects the battery from the vehicles ground and thus eliminates quiescent current drain during delivery. The relay must be removed before delivery to the customer. For more information, refer to the PDI (pre-delivery inspection) manual.

Battery Monitoring System





The battery monitoring system module measures battery current and voltage, which it communicates to the CJB (central junction box) over a LIN (local interconnect network) bus connection. The CJB (central junction box) transmits the battery information to the instrument cluster over the medium speed CAN (controller area network) bus. The instrument cluster acts as a gateway between the medium and high speed CAN (controller area network) bus networks, and transmits the battery condition information to the ECM (engine control module) over the high speed CAN (controller area network) bus. Based on the information received from the battery monitoring system module, the ECM (engine control module) will control the output from the generator and request the switching off of electrical loads if necessary.
For additional information, refer to Generator Description and Operation

CAUTION: Due to the self-calibration routine, it is recommended that all power supply diagnostic testing is carried out using the Jaguar approved diagnostic system rather than a digital multimeter.
The battery monitoring system module is able to generate DTC (diagnostic trouble code)'s to help diagnose battery or generator power supply issues. These DTC (diagnostic trouble code)'s can be read using the Jaguar approved diagnostic system. The Jaguar approved diagnostic system can also be used to implement a battery and generator self test routine. For additional information, refer to Battery
If a fault is detected, the ECM (engine control module) will override the battery monitoring system module.
The battery monitoring system module DTC (diagnostic trouble code)'s can be used to help diagnose battery or generator power supply faults. The DTC (diagnostic trouble code)'s are stored in both the CJB (central junction box) and the ECM (engine control module). The Jaguar 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 battery monitoring system and generator LIN (local interconnect network) bus controlled functions to provide current flow information and will detect if the battery monitoring system or generator are functioning correctly.

BATTERY JUNCTION BOX





Mounted on the LH (left-hand) side of the battery is the BJB (battery junction box). The BJB (battery junction box) contains three megafuses delivering battery power to: the starter motor (400 A); the AJB (auxiliary junction box) (175 A) and the CJB (central junction box) (175 A). For more information, refer to the Electrical Guide.

AUXILIARY JUNCTION BOX





The AJB (auxiliary junction box) is mounted on the passenger compartment rear bulkhead and secured by two nuts/studs. The junction box can be accessed by opening the center panel of the rear seat back. The center panel is secured in position by a single stud at the top, and hinged at the bottom.
The auxiliary junction box receives electrical power from the BJB (battery junction box) via a 175 A megafuse. For more information on the circuits and systems served by the auxiliary junction box, refer to the Electrical Guide.

CENTRAL JUNCTION BOX





The CJB (central junction box) is mounted at the base of the LH (left-hand) A pillar and secured by two nuts/studs. Access to the CJB (central junction box) can be gained through a removable panel located below the LH (left-hand) side of the instrument panel.
The CJB (central junction box) receives electrical power from the BJB (battery junction box) via a 175 A megafuse. A second power supply lead 'daisy chains' off the CJB (central junction box), providing electrical power to the power distribution box. For more information on the circuits and systems served by the CJB (central junction box), refer to the Electrical Guide.
The CJB (central junction box) also controls the functionality of a number of vehicle systems. These include:
- Electric steering column lock. For additional information, refer to Steering Column Description and Operation
- Instrument cluster and panel illumination. For additional information, refer to Instrument Cluster and Panel Illumination
- Exterior lighting systems. For additional information, refer to Exterior Lighting
- Interior lighting systems. For additional information, refer to: Interior Lighting (417-02 Interior Lighting, Description and Operation).
- Active anti-theft alarm system. For additional information, refer to Anti-Theft - Active Anti-Theft - Active
- Passive anti-theft alarm system. For additional information, refer to Anti-Theft - Passive Anti-Theft - Passive
- Electric seats. For additional information, refer to Seats Description and Operation
- Electric windows. For additional information, refer to: Glass, Frames and Mechanisms (501-11 Glass, Frames and Mechanisms, Description and Operation).
- Wipers and washers. For additional information, refer to: Wipers and Washers (501-16 Wipers and Washers, Description and Operation).

POWER DISTRIBUTION BOX





The power distribution box is located in the LH (left-hand) rear of the engine compartment, beneath a closing panel. The power distribution box is supplied electrical power from the BJB (battery junction box), via the CJB (central junction box). For more information on the circuits and systems served by the power distribution box, refer to the Electrical Guide.

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