B102C

Code

Generic B — Body

Body Control Module Internal Fault

Brand: Generic

Type: B — Body

Views: UK: 8 EN: 10 RU: 9

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Page language: EN

Causes

Corrupted or failed BCM software/firmware
Internal BCM hardware failure (electronic component damage)
Low or unstable vehicle battery voltage during operation or programming
Corroded, loose, or damaged BCM connectors or wiring
Water intrusion or physical damage to the BCM
Electrostatic discharge (ESD) or transient voltage event

Symptoms

One or more body systems nonfunctional or intermittent (lights, door locks, windows, wipers, HVAC controls)
Multiple body-related warning messages or lamp(s) on dash
Loss of remote/keyless functions or immobilizer anomalies
Intermittent or complete loss of communication with BCM on scan tool (no responses/Alive messages)
Unexplained battery drain or parasitic current draw

What to check

Read and record freeze frame and full DTC report with a capable scan tool (check for related codes)
Confirm battery voltage and state of charge (measure at battery and BCM connector)
Visually inspect BCM and harness for water damage, corrosion, bent pins, or loose connectors
Check grounds and power feeds to the BCM for proper continuity and low resistance
Check CAN and LIN bus wiring, termination resistances, and idle voltages with scope or multimeter
Attempt to communicate with BCM using manufacturer-level diagnostic equipment (module present, software version, reflash availability)

Signal parameters

Battery/ignition supply voltage to BCM (V)
BCM ground resistance / continuity (ohms)
CAN bus idle voltages (≈2.5V on each high/low differential reference) and differential activity (mV)
LIN bus idle voltage and message activity (V and message presence)
BCM module presence/Alive counter or response to diagnostic requests
Software/firmware part number and calibration level

Diagnostic algorithm

Connect a full-function scan tool and record DTC B102C plus any other stored/pendings. Save freeze-frame and data. Clear codes and see if B102C returns.
Verify battery voltage (>=12.4V recommended for diagnosis) and check charging system. Stabilize supply with a battery charger if required.
Visually inspect BCM enclosure and connectors for corrosion, water entry, damage, or bent pins. Repair or clean connectors as needed, then retest communication.
Verify power and ground circuits to the BCM: measure supply voltage at BCM connector with ignition on and check ground continuity to chassis.
Check vehicle network health: verify CAN/LIN bus physical layer (termination, idle voltages) and observe traffic with scope/scan tool. Repair wiring faults and recheck.
If module communicates, read software/firmware IDs and check for available software updates or known TSBs. Reflash/reprogram BCM per manufacturer procedures where applicable.
If intermittent or no communication persists, perform bench tests or substitute a known-good BCM if available (observe immobilizer/anti-theft precautions—do not replace without proper reprogramming).
If BCM is confirmed internally faulty after above checks, replace or return for repair/reprogramming following manufacturer pairing/security procedures.
After repair or reflash, clear codes, perform relearn procedures required for vehicle, and road-test to confirm normal operation and no reoccurrence.

Likely causes

BCM software corruption or failed update/flash
Internal electronic component failure in BCM
Poor battery/charging system voltage or grounding issue
Corroded/damaged connector or wiring to BCM
CAN/LIN bus short, open or high resistance causing internal error

Fault status

⚠️ Status

Internal fault detected inside the Body Control Module. The module reports an internal hardware or software error requiring further diagnosis of power, grounds, communications, and possible module repair or reprogramming.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5-3.0 hours