B0265

Code

Generic B — Body

Body Control Module (BCM) Communication Fault

Brand: Generic

Type: B — Body

Views: UK: 25 EN: 29 RU: 19

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Instrument cluster or body features (lights, locks, windows) may be inoperative or intermittent
Multiple related communication DTCs present
Inability to communicate with BCM using a scan tool
Random or persistent warning lights
Central convenience features (remote entry, alarm) nonfunctional
Possible drivability or immobilizer issues if BCM interfaces with powertrain/security systems

Scan vehicle and read all stored and pending codes; note freeze frame and related comm codes
Attempt to communicate with BCM using dealer-level or factory scan tool
Check battery state-of-charge and system charging voltage (12.4–12.8 V resting; ~13.5–14.7 V running)
Inspect BCM fuses, relays, and fusible links
Visually inspect BCM connector(s) and wiring for corrosion, bent pins, water intrusion, or damage
Check chassis and engine grounds related to BCM

CAN bus idle voltages: CAN_H and CAN_L should be near the nominal recessive level (~2.5 V each) — differential ~0 V idle
Dominant state shows expected differential (CAN_H rises, CAN_L falls) when messages transmit; use oscilloscope for proper waveform
Presence of expected periodic CAN message IDs from BCM (IDs and rates vary by vehicle) when monitored with a bus analyzer
LIN bus idle typically pulled to battery voltage through pull-up; dominant active pulses will be low
No sustained low-resistance short to battery or ground on either bus line

Confirm B0265 is current or pending; record freeze-frame and check for other U/B codes.
Verify battery voltage and charging system. Recharge/test battery if low; retest with known-good supply if intermittent voltage present.
Check BCM power, ground, associated fuses/relays. Repair any open or high-resistance connections.
Visually inspect BCM connectors and wiring harness for corrosion, water damage, pin damage or loose terminals. Repair as needed.
Attempt communication with BCM via scan tool. If no communication, try accessing gateway or other modules to determine scope of bus failure.
Measure CAN_H and CAN_L (or LIN) voltages at the BCM connector with multimeter; compare to vehicle specification. Use an oscilloscope to inspect waveform quality and message activity if available.
If bus shows short/low resistance, isolate segments by disconnecting modules or harness sections until short is localized. Repair wiring or replace damaged components.
If another module places bus in error (bus-off), identify and repair that module or its wiring before replacing BCM.
If wiring and power/ground are good and problem persists, consult manufacturer service information for BCM programming or known issues. Replace BCM only after confirming hardware fault; program/configure new BCM as required.
Clear codes, re-test all affected functions and monitor bus communication for intermittent faults.