B13C3

Code

LAND ROVER B — Body

Dual battery module - fuse box of dual battery Dual battery module

Brand: LAND ROVER

Type: B — Body

Views: UK: 27 EN: 35 RU: 29

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Page language: EN

Causes

Blown fuse in dual-battery fuse box
Poor or corroded connection at fuse box or battery terminals
Damaged wiring or chafe to harness feeding the dual-battery module
Water ingress into fuse box or module connector
Faulty dual-battery control module
Loss of CAN/serial communication between module and vehicle network

Symptoms

Dashboard warning lamp or message about dual battery or charging system
Auxiliary battery not charging or not being used
Vehicle may report electrical subsystem faults or reduced functionality
No-start or difficult start if auxiliary battery is required
Intermittent or permanent fault code stored
Reduced charging system performance

What to check

Read and record all stored and pending DTCs with a capable scan tool (include network codes)
Visually inspect dual-battery fuse box and module for melted plastic, water intrusion or corrosion
Check condition and torque of battery terminals (main and auxiliary) and battery-to-chassis grounds
Inspect wiring harness and connectors for damage, chafe, corrosion or disconnection
Check continuity of suspect fuses and their holders (remove and visually inspect)
Measure static battery voltages (main and aux) and voltage at the module connector with key off and key on/run

Signal parameters

Main battery voltage (key off, key on, engine running)
Auxiliary battery voltage (key off, key on, engine running)
Fuse continuity and voltage drop across fuse/fuse holder
Module supply voltage at connector pin(s)
Ground resistance at module ground (
Charging system output current/voltage (alternator)

Diagnostic algorithm

Connect an appropriate diagnostic tool, read and save all codes and freeze-frame data. Note related network codes.
Visually inspect dual-battery fuse box and module for damage, corrosion, melted fuses, or signs of water ingress. Replace visibly damaged fuses and clean connectors as needed.
With ignition off, check continuity of the suspect fuse(s). Verify correct fuse rating and seating. Replace fuse if blown and test if fault returns.
Inspect and clean battery terminals and grounds. Measure battery voltages (main and auxiliary) with a digital meter (key off, key on, engine running). Record values.
With harness exposed, inspect wiring for chafe, pin damage, or corrosion. Wiggle test connectors while monitoring for voltage or communication dropouts.
Verify ground integrity at module ground point (measure voltage drop while cranking if necessary).
Check charging system (alternator output) to ensure batteries are being charged correctly. Verify diodes/regulator operation if suspect.
Check for CAN/network communication to the dual-battery module using the diagnostic tool; note lost-communication or intermittent messages.
If wiring, fuses, connectors, grounds and charging system are good and communication is present but fault persists, compare module diagnostic data to spec. Consider replacing and programming the dual-battery module per manufacturer procedures.
After repairs, clear codes, perform functional tests (charging and load tests) and road test to verify fault does not return. Document findings and repairs.
Safety note: isolate batteries and follow manufacturer safety procedures before working on battery/fuse box components to avoid shorting, sparks, or injury.

Likely causes

Blown or loose fuse in the dual-battery fuse box
Corroded/loose connector at the dual-battery module or battery terminal
Damaged wiring between battery(s) and module (short/open)
Faulty dual-battery module or internal electronics

Fault status

⚠️ Status

Electrical/communication fault detected in dual-battery module or its fuse box (open/short/intermittent/communication error).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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B13C3 — Dual battery module - fuse box of dual battery Dual battery module