B1D92

Code

LAND ROVER B — Body

Body Control Module — Internal/Communication Fault

Brand: LAND ROVER

Type: B — Body

Views: UK: 7 EN: 13 RU: 7

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Loss of power or poor ground to the BCM
Corroded/damaged BCM connector or wiring
Faulty BCM (internal hardware or software failure)
CAN/LIN bus wiring fault or short to power/ground
Interference or faults from another module on the network
Water ingress or physical damage to BCM

Symptoms

Multiple unrelated electrical faults (locks, lights, windows, alarm, interior modules)
Warning lights related to body systems and communications
Intermittent or permanent loss of central locking, interior lighting, wipers etc.
Inability to communicate with the BCM using diagnostic tool
Vehicle may go into reduced functionality or security/immobilizer states

What to check

Read and record all stored and pending DTCs and freeze-frame data from all networks
Check battery state-of-charge and charging system voltage (should be ~12.4–14.7 V with engine running)
Inspect BCM connectors for corrosion, bent pins, water ingress, or loose locking tangs
Verify engine/chassis ground points and BCM ground continuity to battery negative
Check relevant fuses/relays for BCM power feeds
Scan the CAN/LIN bus using a capable diagnostic scanner to see if BCM messages are present

Signal parameters

Battery/BCM supply: nominal 9–16 V (depending on system state); voltage should be stable
Ground: near 0 Ω continuity to battery negative; no high resistance
CAN bus idle voltages: CAN_H ≈ 2.5–3.5 V, CAN_L ≈ 1.5–2.5 V (each module measured to chassis), differential ~0 V idle, ~2 V dominant — verify with scope
Bus message rate: compare BCM message IDs and expected frequency to manufacturer specification using a scanner
LIN: logic-level pulses; check for expected awake/sleep behavior and node responses
Diagnostic response: BCM should respond to OBD tool queries; lack of response indicates comms or internal fault

Diagnostic algorithm

Read DTCs from all modules and note freeze-frame/live data. Save results.
Check battery voltage and charging. Ensure good battery condition and correct terminal tightness.
Inspect BCM connector and wiring for damage, corrosion or water. Disconnect battery before physical connector repairs.
Verify BCM power and ground circuits: measure supply at BCM harness and continuity to chassis ground.
Check fuses/relays feeding the BCM. Replace any blown or suspect fuses and retest.
With ignition on, use an advanced scan tool to request BCM data and monitor CAN/LIN traffic. Confirm whether BCM is transmitting and receiving expected message IDs and frequencies.
Use an oscilloscope to inspect CAN_H/CAN_L waveforms for noise, bus-off conditions, dominant/recessive levels and error frames. Repair wiring/shorts if present.
Disconnect any recently added aftermarket devices that could interfere with vehicle networks and retest.
If wiring and power/ground ok and communications remain faulty, check for available software updates or service bulletins and perform BCM software reflash if specified by manufacturer.
If reflashing fails or diagnostics point to internal module fault, replace and program a new or known-good BCM per manufacturer procedures. After replacement, clear codes and verify system functionality and network stability.
Road-test and re-scan to confirm issue is resolved and codes do not return.

Likely causes

Battery voltage low or intermittent supply to BCM (loose battery terminal, weak battery)
Poor chassis or engine ground at BCM ground point
Corrosion or bent pins at the BCM multi-pin connector
Short, open or high-resistance on CAN high/low or LIN wiring
Aftermarket electronic device interfering with vehicle network
BCM internal component failure or corrupted software

Fault status

⚠️ Status

Set when the BCM detects an internal electronics fault or loss/degradation of communication on its network. May be stored as active, intermittent or permanent depending on occurrence. Freeze-frame and live data may be available; further diagnostics required to isolate cause.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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