B00CD

Code

Generic B — Body

Body Control Module Communication Fault

Brand: Generic

Type: B — Body

Views: UK: 13 EN: 16 RU: 13

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open, short or high resistance in BCM power or ground circuits
Damaged, corroded or loose BCM connectors or wiring harness
Faults on the vehicle communication bus (CAN, LIN): short to battery/ground, open, or failed termination
BCM software or internal hardware failure
Incorrect configuration or coding after module replacement or software update
Aftermarket devices or improper installations interfering with bus traffic

Symptoms

BCM-dependent systems inoperative or intermittent (door locks, interior lights, wipers, lighting)
Multiple modules report lost-communication or related U/B codes
Instrument cluster warnings, erratic indicators or chimes
Remote keyless entry or alarm may not function
Possible parasitic battery drain or inability to go to sleep
Inability to communicate or reprogram the BCM with a scan tool

What to check

Read all stored and pending DTCs and freeze frame data with a diagnostic scanner; note related U- and B-codes
Confirm ability to communicate with the BCM using dealer or aftermarket scan tool (wake/refresh module)
Check vehicle battery voltage (12.4–12.8 V at rest) and charging system health
Inspect BCM fuses, fusible links and related power distribution for continuity and correct rating
Visually inspect BCM connector(s) for corrosion, water intrusion, bent pins, or damage
Check for recent work or aftermarket accessories spliced into wiring near the BCM

Signal parameters

Battery supply to BCM: VBATT (approx. 12 V at key off; >13 V with engine running)
Ground continuity and measured voltage drop on BCM ground circuit
CAN high/low idle voltages (~2.5 V common-mode; differential behavior during dominant recessive states)
CAN bus data rate (e.g., 125 kb/s, 500 kb/s) and expected message periodicity for BCM message IDs
Bus error counters (CAN error frames, TX/RX error counts) and checksum/CRC status for messages
LIN wake/sleep signals and expected idle voltage levels

Diagnostic algorithm

Connect a capable diagnostic scanner, record B00CD plus all related DTCs and freeze frame data; note events/timestamps.
Attempt to communicate with the BCM; if communication is intermittent or absent, try a different known-good scanner or OEM tool to rule out tool compatibility.
Check battery voltage and charging system; ensure stable supply before further testing.
Verify BCM power and ground fuses; measure VBATT at the BCM power pin and check ground continuity to chassis. Repair loose/ corroded connections.
Visually inspect BCM connectors and harness for corrosion, water entry, damaged insulation, or pin damage. Repair or replace damaged connectors/wiring.
While monitoring live data, observe CAN/LIN bus voltages at the BCM connector: check for stuck dominant state (one side shorted), correct idle voltages, and compare to another node.
Measure bus termination resistance (approx. 60 ohm between CANH and CANL with ignition off on most systems); remove modules if necessary to isolate a shorted node.
Perform wiggle tests on harness while observing communication and error counters to reproduce the fault; repair any wiring breaks or intermittent connectors found.
Disconnect aftermarket modules or recent installations that share the bus and retest.
If wiring and connectors are good, verify BCM software/calibration and coding. Re-flash or reprogram only using OEM procedures if required.
If communications are still not restored after harness, power/ground and reprogram checks, bench-test or replace the BCM as a last step. Ensure correct programming and module matching after replacement.
Clear codes and road-test; monitor for reappearance and verify all BCM functions.

Likely causes

Poor BCM ground or battery feed (corrosion, loose terminal, blown fuse)
Damaged BCM connector (corrosion, bent pins) or wiring to nearby modules
CAN/LIN bus shorted to battery or ground, or failed termination resistor
Recent module reflash/config error or incompatible BCM replacement
BCM internal failure (less likely than wiring/connectors)

Fault status

⚠️ Status

Body Control Module Communication Fault — diagnostic indicates missing, corrupted or failed responses/messages from the BCM on the vehicle communications bus; may be stored as intermittent or permanent depending on fault persistence.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours