B2062

Code

Generic B — Body

Body Control Module (BCM) Communication Fault

Brand: Generic

Type: B — Body

Views: UK: 4 EN: 3 RU: 7

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Page language: EN

Intermittent or complete loss of door locks, lighting, wipers, or other body functions
Keyless entry, remote start, or immobilizer issues
Dash warning lights related to body systems
Inability to communicate with BCM via scan tool
Modules reporting intermittent or multiple communication-related codes

Read all stored and pending codes from all modules; note freeze frame and occurrence counts
Verify battery voltage and charging system operation (12.4–14.4 V typical) before testing
Check BCM power and ground circuits and related fuses/relays
Visually inspect BCM connector(s) for corrosion, bent pins, or water intrusion
Scan other modules for loss-of-communication U-codes to identify bus-wide issues
Measure CAN/LIN bus voltages at BCM connector with key on and engine off

CAN bus recessive voltage: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (both lines equal)
CAN bus dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
Termination resistance: approx. 60 ohms across CAN_H to CAN_L (two 120Ω in parallel)
LIN bus idle: single-wire ~battery voltage when idle (varies by manufacturer)
Expected steady bus activity while key on: periodic packet traffic; total bus silence may indicate module or power loss

Connect a capable scan tool and retrieve all BCM and network codes. Note occurrence, freeze data, and any related U-codes.
Verify battery voltage ≥12.4 V and charge if necessary. Perform tests with nominal battery voltage.
Inspect BCM fuse(s), relays and power/ignition feeds. Repair any open circuits and retest communications.
Visually inspect BCM connector and wiring harness for damage, corrosion, or water ingress. Repair or clean as needed.
With key on, measure CAN_H and CAN_L at the BCM connector: confirm recessive and dominant voltages and check termination resistance (~60 Ω).
If bus voltages abnormal, trace wiring for short to battery/ground or open circuit. Isolate sections by disconnecting nearby modules to locate fault.
If bus electricals are correct, verify whether other modules respond on the network. If only BCM is non-responsive, try re-seating connector and perform a wiggle test while monitoring communication.
Check for aftermarket devices tied into the bus and disconnect them. Re-scan for communication restoration.
If BCM power/ground and bus wiring are correct but BCM still fails to communicate, check for available BCM software updates or reprogramming procedures per manufacturer service information.
If reprogramming not possible or unsuccessful and all wiring/other modules verified good, replacement of BCM may be required. After repair, clear codes and confirm normal operation and network communications.