B1C87

Code

Generic B — Body

Body Control Module Internal Error

Brand: Generic

Type: B — Body

Views: UK: 12 EN: 14 RU: 10

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Corrupted or failed BCM firmware/firmware update
Internal microcontroller, memory (EEPROM/FLASH) or PCB component failure
Intermittent or low supply voltage to the BCM (battery, charging system, poor connections)
Poor ground or a corroded/damaged connector at the BCM
Water ingress or physical damage to the BCM housing
Aftermarket accessory wiring causing voltage spikes/noise

Symptoms

Multiple unrelated body systems fail or behave erratically (locks, lights, wipers, windows)
Module not responding to diagnostic tool or intermittent communication with scan tool
Illumination of body or general warning lights on dash
Stored communication errors (CAN/LIN) or other module DTCs alongside B1C87
Vehicle may fail to enter/exit sleep or have parasitic battery drain

What to check

Use a capable scan tool to read all DTCs from BCM and other network modules; record freeze frame and event counters
Verify BCM responds to diagnostics (CAN/UDS/ISO requests) and check software/calibration ID
Measure battery voltage at rest, key ON, and engine running; verify charging system
Inspect BCM connectors and harness for corrosion, bent pins, water intrusion, heat damage or aftermarket splices
Check main ground(s) and power supply circuits for continuity and low resistance to chassis/battery
Monitor CAN/LIN bus for errors, bus-off events and proper recessive/dominant voltages; check for other modules reporting comm faults

Signal parameters

BCM supply voltage (battery rest, key ON, engine running)
BCM ground circuit voltage/drop under load
CAN bus recessive voltage (~2.5 V) and CAN_H/CAN_L differential during communication
CAN error counters / bus-off status and message frequency for BCM TX/RX
BCM internal status flags (watchdog, EEPROM checksum, bootloader status) if available via diagnostics
BCM software/calibration ID and software update availability

Diagnostic algorithm

Confirm the customer complaint and attempt to reproduce the symptom. Note when the fault occurred and any recent battery/repair history.
Connect a scan tool and read all DTCs from the BCM and network modules. Save freeze frame and status bits. Note whether BCM responds consistently.
Check battery condition and charging system: measure resting voltage (>12.4 V preferred), key ON and engine running. Recharge or load-test battery if marginal.
Visually inspect BCM and harness: unplug module and inspect pins for corrosion, bent pins, water damage or contamination. Repair any damaged connectors and retest.
Verify power and ground: measure voltage at module power pins and resistance from module ground to battery negative. Repair poor connections before further testing.
Monitor CAN/LIN bus with oscilloscope or capable tool: verify recessive voltage and differential signals during communication; look for noise, stuck dominant, or bus-off conditions.
Clear DTCs and perform key cycles/drive cycle that reproduces the fault. If code returns, capture freeze frame and data on return to identify triggers.
Check for available software updates or reflash procedures from manufacturer. If recommended, reprogram BCM following factory procedures (ensure stable power source and battery charger).
If reflash fails or errors persist after addressing wiring/power/communication issues, consider BCM bench testing or replacement. Replace BCM only after confirming it is the root cause.
After replacement or reprogramming, configure and code the new module as required for vehicle options, then verify all affected functions and re-scan networks for DTCs.

Likely causes

Power supply disturbance during a module update or vehicle operation (low battery, jump start)
Corrosion or moisture at the BCM connector causing intermittent contacts
BCM firmware corruption (needs reflash or calibration update)
Internal component failure on the BCM printed circuit board
Network errors on CAN or LIN causing the BCM to report an internal fault

Fault status

⚠️ Status

Body Control Module internal error — BCM detected an internal fault (hardware, memory, or firmware). May cause loss or malfunction of multiple body systems; further inspection of power, grounds, connectors, network communications and software is required.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 2.0-4.0 hours