B0147

Code

Generic B — Body

Body Control Module (BCM) Communication Fault

Brand: Generic

Type: B — Body

Views: UK: 7 EN: 13 RU: 5

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty or unprogrammed BCM
Open, short, or high-resistance in CAN/LIN wiring or connectors
Loss of BCM power or ground (battery, fuse, fusible link)
Faulty gateway or other module on the same network causing bus errors
Incorrect or outdated BCM software/configuration
Poor termination or missing CAN/LIN bus resistors

Symptoms

Instrument cluster communication errors or warning message(s) about BCM
Loss of body functions: door locks, interior lighting, wipers, keyless entry, chimes
Intermittent or permanent no-communication with BCM in scan tool
Multiple modules report loss-of-communication faults
Vehicle may exhibit intermittent starts, no crank, or failsafe behavior if BCM involved in immobilizer

What to check

Retrieve all stored codes and freeze frame data from BCM and other modules with a capable scan tool
Record time/date of occurrence and whether issue is present at key-on vs driving
Check battery voltage and charging system (12.4–12.9 V at rest; >13.5 V when running)
Inspect BCM power and ground circuits, fuses, and relays for continuity and proper supply
Visually inspect BCM connectors and harness for corrosion, damage, water intrusion or rodent damage
Check for presence of other U-/B-codes on vehicle network (e.g., U0100, U0073, U0140)

Signal parameters

CAN bus idle voltage: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive)
CAN dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V; differential ≈ 2.0 V
Termination resistance: ≈ 60 ohms across CAN_H and CAN_L (two 120 Ω in parallel)
Common CAN data rates: 125 kbps, 250 kbps, 500 kbps (verify vehicle-specific rate)
LIN bus idle: TX ≈ battery voltage via pull-up; dominant ≈ ~0 V (vehicle-specific)

Diagnostic algorithm

Read and record all DTCs from all modules; do not erase yet. Note if B0147 is current or history.
Check battery state of charge and terminal integrity; restore normal voltage before continuing.
Inspect BCM connectors, fuses, and grounds for corrosion, security and proper mating; repair any physical faults.
With a scan tool, observe communication status and live data. Note whether BCM appears on the bus and if message IDs are present.
Measure CAN_H/CAN_L idle voltages at the BCM connector with ignition ON; compare to expected values in signal_params.
Measure termination resistance across CAN_H and CAN_L with ignition off; expect ≈60 Ω. Check for shorts to battery or ground.
Perform continuity and short-to-power/ground checks on wiring from BCM to nearest modules and junctions; repair any faults.
If intermittent, perform backprobe and wiggle test of harnesses while monitoring bus traffic for dropouts.
Isolate segments by disconnecting nodes sequentially (other modules, gateways) to locate a misbehaving bus device.
If wiring and other modules test good, check BCM software/calibration level and update/reflash per manufacturer procedure.
If BCM still fails communication after software update and bench/power tests, consider replacement and reprogramming per OEM procedures; verify all functions after repair.
Clear codes and road-test to confirm repair. If fault returns, repeat isolation focusing on intermittent or environmental causes.

Likely causes

Damaged/loose BCM connector or ground
Battery low voltage or weak battery causing module resets
Short or open on CAN_H, CAN_L or LIN conductor near BCM
Other control module driving bus into error state (e.g., stuck dominant)
BCM internal hardware fault or memory corruption

Fault status

⚠️ Status

B0147 — Body Control Module (BCM) Communication Fault: BCM is not communicating correctly on the vehicle network or has failed its internal communication checks.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5 - 4.0 hours