Code
B0411
Generic
B — Body
Body Control Module Communication Circuit Fault
Views:
UK: 1
EN: 1
RU: 1
AI status
Completed
Completed
100%
Causes
- Damaged, corroded, or loose BCM connectors or harness
- Open, shorted or high-resistance wiring on the vehicle communication bus (CAN/LIN)
- Failed or intermittent BCM (internal fault)
- Blown fuse, poor battery connection or weak battery voltage
- Faulty termination resistors or improper bus topology
- Water intrusion or corrosion in connectors
Symptoms
- Intermittent or complete loss of body functions (locks, lights, windows, wipers)
- Multiple network-related DTCs present (U-codes or other B-codes)
- No response from remote/keyless functions
- Dashboard warning messages about communication faults
- Certain modules not appearing on a scan tool or responding slowly
What to check
- Scan for all stored and pending DTCs on BCM and other modules; record freeze-frame data
- Verify battery voltage stable (12.4–14.7 V) during tests
- Visually inspect BCM connectors, wiring, and sealing for corrosion or damage
- Check fuses and BCM power/ground circuits for continuity and proper voltage
- Use a scan tool to monitor live data and module presence on the bus
- Measure CAN/LIN bus voltages with ignition on: CAN recessive ≈2.5 V (each line), CAN_H ≈3.5–4.0 V & CAN_L ≈1.0–1.5 V when dominant; LIN idle ≈battery voltage, dominant ≈0–1 V
Signal parameters
- CAN bus idle (recessive): each line ≈2.5 V
- CAN bus dominant: CAN_H ≈3.5–4.0 V, CAN_L ≈1.0–1.5 V (differential ≈2.0–3.0 V)
- Typical CAN data rates: 125 kb/s, 250 kb/s, 500 kb/s (verify vehicle-specific)
- LIN bus idle: ≈battery voltage (dominant ≈0–1 V)
- Watch for excessive message errors, lost frames, or lack of node heartbeat messages
Diagnostic algorithm
- Retrieve and record all related DTCs from BCM and other modules; note time/freeze data.
- Verify battery state of charge and charging system; ensure stable voltage during testing.
- Perform visual inspection of BCM, connectors, and harness for damage, corrosion or moisture.
- Check power and ground circuits to BCM: measure voltages and continuity to chassis ground.
- Confirm fuses and relays feeding the BCM are good and supplying proper voltage.
- Using a scan tool, verify which modules are present on the network and monitor live bus error counters.
- Measure CAN/LIN bus voltages at the BCM connector and at other nodes; compare to expected signal parameters.
- If intermittent, perform wiggle tests and backprobe while operating functions or monitoring the bus; note changes.
- Isolate segments by disconnecting suspected modules or aftermarket devices to see if the fault clears; inspect termination resistors.
- If wiring or connectors are faulty, repair or replace damaged sections and protect against moisture; then clear codes and re-test.
- If wiring and power/ground are good and fault persists, check for required BCM software updates or configuration; if confirmed failed, replace BCM according to manufacturer procedure and reprogram.
- After repairs, clear DTCs and confirm restoration of normal network communications and vehicle functions.
Likely causes
- Corroded/loose BCM connector or ground
- Open/short on CAN high or CAN low between BCM and gateway
- Missing/failed bus termination resistor(s)
- Intermittent battery/ignition power to BCM
- Faulty BCM or recent incorrect module programming
Fault status
Status
BCM detected interrupted, absent, or invalid messages on the body communication circuit. Fault set when communication errors or loss exceed the module's threshold.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
Similar codes
Workshop Manuals
Available brands with manuals
2
AUDI 11
6-speed manual gearbox 0B1, front-wheel drive — Workshop Manual (Edition 05.2014)
Workshop Manual199,00 UAH
Audi A3 (1997) – 1.6L 4-cylinder (2‑valve) Engine Mechanical Components Service Manual (AEH, AKL, APF) – Edition 07.2002
Workshop Manual199,00 UAH
AUDI A3 (2004) Workshop Manual — 2.0L FSI Turbo (4‑cyl, 4‑valve) Engine, Mechanics — Edition 03.2017
Workshop Manual199,00 UAH
Audi A3 2004 — Electrical System (Workshop Manual, Edition 02.2018)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet – 4.2 l V8 (5‑valve, timing chains) – Workshop Manual (Mechanics) – Edition 04.2007
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet — Auxiliary Heater Workshop Manual (Edition 08.2004)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet (1.8T 4‑cyl turbo) — Motronic Injection & Ignition System Service Manual (Edition 01.2015)
Workshop Manual199,00 UAH
Audi A8 (2003) — Electrical System Workshop Manual (Edition 08.2014)
Workshop Manual199,00 UAH
Audi Q4 e-tron (Type F4) - Self-study Programme SSP 685
Workshop Manual199,00 UAH
Audi Q8 (2018) — Electrical System Workshop Manual (Edition 05.2019)
Workshop Manual199,00 UAH
Audi Servicing Manual — 7‑Speed Dual Clutch Transmission 0CJ / 0CL / 0CK / 0DN / 0DP / 0HL (Edition 05.2018)
Workshop Manual199,00 UAH
LAND ROVER 3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email
