B115D

Code

Generic B — Body

Body Control Module Internal Fault

Brand: Generic

Type: B — Body

Views: UK: 10 EN: 17 RU: 11

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Page language: EN

Causes

BCM internal hardware failure (processor, memory, internal power regulator)
Corrupted or failed BCM firmware/software
Loss or fluctuation of supply voltage (battery/charging system) during write/update
Poor power/ground connections or damaged BCM connector
Water intrusion or corrosion inside BCM or connector
Electric overstress from jump-starting, aftermarket accessory, or short circuit

Symptoms

Multiple body features fail or work intermittently (locks, lighting, wipers, windows)
Malfunction indicator lights or BCM-related warnings on dash
Loss of communication with BCM on scan tool or intermittent CAN network errors
Vehicle may not respond to keyless entry or may experience security/immobilizer issues
Parasitic battery drain or unexpected battery discharge

What to check

Read and record all stored/active DTCs and freeze frame data with a capable scan tool
Attempt to communicate with BCM; note any 'no response' or timeout codes
Check battery voltage (static ~12.6 V, cranking >9 V) and charging system operation
Inspect BCM connector and harness for corrosion, water ingress, damaged pins, or loose terminals
Verify all BCM-related fuses and relays are intact and have good connections
Measure BCM supply voltage and ground resistance at the module

Signal parameters

BCM supply voltage: nominal ~12.0–14.5 V (verify key-on and cranking values)
BCM ground continuity: low ohms (
CAN bus idle voltages: CAN_H ~2.5–3.5 V, CAN_L ~1.5–1.0 V (verify differential signaling with oscilloscope)
Wake/sleep line states (when applicable) per vehicle spec
LIN or other body network voltages per manufacturer specification
Scan-tool communication response time and frequency of communication timeouts

Diagnostic algorithm

Confirm code presence: connect OEM-capable scanner, record B115D and any companion codes, note freeze frame and occurrence history.
Clear codes and re-test: clear DTCs, cycle ignition, and operate affected systems to see if B115D returns.
Battery and charging check: verify good battery state-of-charge and charging system; recharge or replace weak battery before further diagnostics.
Visual inspection: inspect BCM enclosure and connector for water, corrosion, burned pins, bent terminals, or damage; repair harness as needed.
Power/ground verification: measure voltage at BCM power pins (key off/key on/crank) and check ground resistance to chassis/battery negative.
Network check: verify CAN/LIN integrity—measure idle voltages, check for short to power/ground, and look for bus errors with scope or network tester.
Remove external causes: disconnect aftermarket accessories and retest; inspect circuits for shorts or backfeeding that could corrupt BCM.
Software/service history: check for available TSBs and confirm BCM software level; if corrupted or out-of-date, attempt reflash/update with OEM tool.
Reprogram or reset: attempt a controlled reprogram/reflash only with proper OEM tooling and battery support (avoid interruptions).
Replacement consideration: if reflash and wiring/power/network checks are good and fault persists, prepare to replace BCM; verify calibration, coding, and security (immobilizer) procedures before installation.
Post-repair verification: after repair/replacement, clear codes, reprogram as required, and perform full system test and road test to confirm no recurrence.

Likely causes

Corrupted firmware after failed update or power interruption
Intermittent or low battery/charging voltage causing memory errors
Damaged BCM connector or wiring (moisture/corrosion)
Internal component failure due to age, manufacturing defect, or electrical spike