B002B

Code

Generic B — Body

Body Control Module Internal Fault

Brand: Generic

Type: B — Body

Views: UK: 8 EN: 12 RU: 13

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Page language: EN

Causes

BCM internal hardware failure (processor, memory, or board components)
Corrupted firmware or failed module software update
Intermittent or low battery voltage, voltage spikes or transients
Poor power/ground connections or blown fuses
Water intrusion, corrosion, or physical damage to BCM or connectors
Faulty wiring harness or pin damage at BCM connectors

Symptoms

Multiple body functions inoperative or intermittent (door locks, lighting, wipers, windows)
Dash warning lights or message about module fault or service required
Loss or degradation of CAN/LIN communications with other modules
Intermittent starting or accessory function issues tied to BCM outputs
Parasitic battery drain or unexpected battery discharge
Stored additional communication or subsystem DTCs

What to check

Retrieve and record all stored codes and freeze-frame data with a qualified scan tool
Check battery state-of-charge and system voltage (engine off and cranking)
Inspect BCM fuses, fusible links and power distribution for continuity
Visually inspect BCM connectors for corrosion, water intrusion, bent pins or damage
Verify good ground(s) at BCM and vehicle chassis (measure
Check CAN/LIN bus for activity and bus voltages with a scope or bus monitor

Signal parameters

VBAT / Ignition supply voltage to BCM (expected ~12–14 V depending on state)
BCM internal supply rails (if available via manufacturer data)
Module wake/sleep commands and response times on CAN/LIN
CAN bus dominant/recessive voltages (~2.5 V idle on CAN_H/CAN_L differential ~2.5 V each; check for activity)
Ground voltage difference between BCM ground and chassis (
Module uptime, last reset count, checksum or error counters (from scan tool)

Diagnostic algorithm

Read and record all DTCs and freeze-frame with a professional scan tool; note related U- or P-codes.
Verify battery condition and system voltage; charge or replace battery if low and re-check.
Perform visual inspection of BCM and harness: look for moisture, corrosion, damaged pins, or loose connectors; repair as needed.
Check fuses and power feeds to the BCM for continuity and correct voltage with ignition ON and OFF.
Verify ground integrity: measure resistance from BCM ground to chassis and check for voltage drops while operating circuits.
Monitor CAN/LIN bus for proper activity and voltages; identify any bus short or high-load device disrupting communication.
If power/ground/communication are good, attempt to clear codes and reproduce fault; if intermittent, record conditions when it occurs.
Check module software/firmware level against manufacturer service information and known TSBs; apply recommended updates or reflash using OEM procedures.
If reflash fails or errors persist after good supply and communications, consider module removal for bench testing or replacement. Follow OEM procedure for programming and immobilizer pairing when replacing.
After repair or replacement, verify operation of all affected systems, clear codes, and perform a full system test and road test.

Likely causes

Loss of stable VBAT or ignition supply to BCM (bad fuse, loose terminal)
Faulty or intermittent ground at BCM
Corroded or contaminated BCM connector pins
BCM firmware corruption or failed reflash/update
Internal BCM component failure (requires bench test/replacement)

Fault status

⚠️ Status

Internal fault detected in Body Control Module (BCM). Inspect BCM power, grounds, connectors, communications and software. Module repair or replacement and reprogramming may be required.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1–4 hours