B00A3

Code

Generic B — Body

Body Control Module Internal Fault

Brand: Generic

Type: B — Body

Views: UK: 6 EN: 10 RU: 7

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Corrupted BCM firmware or flash memory
Internal electronic component failure within BCM (MCU, power regulator, watchdog)
Intermittent or low supply voltage during module operation (brown-out)
Electrical overstress from jump-start, battery surge, or lightning
Water intrusion or physical damage to BCM housing or connectors
Connector/circuit short to battery or ground causing internal damage

Symptoms

One or more body functions intermittent or not working (locks, windows, wipers, interior lights)
Loss of remote keyless entry or immobilizer-related issues
Multiple module communication errors reported on scan tool (CAN/LIN)
Warning messages or instrument cluster notifications about BCM or systems controlled by BCM
Unpredictable behavior of lighting, chimes, or convenience features
Possible inability to program keys or reflash modules

What to check

Read all stored DTCs and freeze frame data from BCM and other network modules
Check battery voltage (engine off and cranking) and charging system health
Inspect BCM connector(s) for corrosion, bent pins, water damage, or loose terminals
Verify BCM power and ground circuits (fuses, relays, continuity to battery)
Scan CAN/LIN bus for bus errors, missing nodes, or high error counters
Check for recent bodywork or water exposure that could have affected BCM

Signal parameters

Battery supply (VBATT): nominal 12–14.5 V (engine running ~13.5–14.5 V); avoid 15.5 V
Ignition/switched power: present when ignition ON; verify stable
Ground resistance: low ohms to chassis/battery negative
CAN_H/CAN_L idle voltages: ~2.5 V each; differential ~0 V, dominant ~2.5 V/1.5 V on activity
LIN bus levels (if present): expected low/high voltages per vehicle spec
Internal temperature (if available): verify not exceeding operating limits

Diagnostic algorithm

Connect manufacturer-capable scan tool and read BCM fault code(s) and freeze frame data. Note any related network or module codes.
Attempt to clear the code and see if it returns immediately or intermittently. If it returns, proceed with hardware checks.
Check battery state-of-charge and charging system. Recharge or load-test battery if needed and re-check code.
Visually inspect BCM and connectors for moisture, corrosion, heat damage or bent pins. Repair/clean connectors and secure grounds.
Verify BCM power and ground circuits: check fuses, relays, connector pin voltages and ground continuity to chassis/battery negative.
Monitor CAN/LIN network for errors and confirm BCM is present and responding on the bus. Use oscilloscope or diagnostic tool to view bus traffic.
Check for intermittent wiring faults: wiggle test harnesses while monitoring BCM presence and voltages.
If hardware checks pass, check BCM software/calibration version against current releases and TSBs. Reflash or update software per manufacturer procedure.
If reflash fails or module reports internal hardware faults after software attempts, consider replacement of BCM and programming/configuration to vehicle.
After repair or replacement, re-scan all modules, clear codes, verify proper operation of body functions, and road/test to confirm issue resolution.

Likely causes

BCM detected checksum/CRC error in internal flash memory
Processor lockup or repeated watchdog resets
Voltage spike caused by faulty charging system or external surge
Corroded/wet connector causing intermittent power or ground
Failed onboard voltage regulator or power transistor
Software bug after recent update or incomplete reflash

Fault status

⚠️ Status

Internal BCM self-diagnostic fault stored. Module detected an internal error (memory/processor/watchdog) that may impair body function control or communications. Repair actions typically include hardware inspection, power/ground verification, software reflash, or BCM replacement and reprogramming.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 2.0-4.0 hours