B0284

Code

Generic B — Body

Body Control Module (BCM) internal fault

Brand: Generic

Type: B — Body

Views: UK: 11 EN: 22 RU: 13

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Page language: EN

Causes

Internal BCM hardware failure (processor, memory, or internal circuits)
Corrupted or failed firmware/calibration
Intermittent or low power supply (battery/stby voltage or ground issues)
Power surge or transient (jump start, short circuit, lightning)
Water intrusion or corrosion inside module or connector
Connector pin damage or poor mating

Symptoms

Illumination of fault/warning indicators on dash (module warning)
Loss or intermittent operation of body functions (locks, lights, wipers, windows, HVAC controls)
No communication with BCM on diagnostic scanner or intermittent CAN/LIN messages
Stored multiple BCM-related DTCs or repeated resets
Erratic behavior of convenience features (remote key, interior lights)

What to check

Read all stored and pending DTCs and freeze frame data with a capable scanner
Check battery state-of-charge and voltage (cranking and key-on)
Verify BCM main power and ground voltages at the module connectors
Inspect BCM and connector(s) for corrosion, water ingress, or physical damage
Check related fuses and relays for BCM supply and accessory circuits
Scan vehicle network for CAN/LIN communication faults or other module errors

Signal parameters

Battery voltage (Key ON): approx. 11–14.5 V
Standby/sleep supply (if equipped): as specified by manufacturer, typically near battery voltage when awake
Ground resistance at BCM: near 0 ohm to chassis; voltage drop
CAN bus idle voltages: CAN high ≈ 2.5 V, CAN low ≈ 2.5 V (differential ~0 V idle); differential ≈ 2.5–3.5 V during activity
CAN bus termination: approx. 60 ohm between CANH and CANL (vehicle dependent)
Supply current: no abnormal parasitic draw from BCM when vehicle is sleeping (manufacturer-specific)

Diagnostic algorithm

Record DTCs, freeze frame, and all related module codes. Note occurrence conditions and module VIN/calibration info.
Attempt to clear codes and recheck if B0284 returns immediately or after specific events.
Verify battery health and voltage with the engine off and key on. Recharge or replace battery if low.
Backprobe and measure BCM supply/ground pins for correct voltages and voltage drop under load.
Visually inspect BCM housing and connector for moisture, corrosion, bent pins, or signs of overheating.
Check fuses/relays for BCM power circuits; replace suspect fuses and retest.
Scan the vehicle network to confirm CAN/LIN communication; use scope if intermittent or noisy signals suspected.
If power/ground and communications are good, consult manufacturer repair information for known software updates or reflash procedures; perform reprogramming if applicable.
If firmware update/reflash does not clear the fault and all wiring/inputs test good, consider controlled replacement of the BCM and program/configure the new module per manufacturer procedures.
After repair or module replacement, verify all body functions and perform final scan; monitor for code recurrence.

Likely causes

Low or intermittent battery/standby voltage to BCM
Poor ground connection at BCM chassis ground
Corroded or damaged BCM connector pins
Module memory/firmware corruption after update or fault
Internal component failure (e.g., EEPROM, MCU, power regulator)
Blown BCM fuse or damaged supply wiring

Fault status

⚠️ Status

BCM Internal Fault — module self-test detected an internal error. Verify power, ground, and communications; inspect for damage or corrosion. Reflash or replace BCM if hardware/firmware failure is confirmed.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1.0-3.0 hours