B1C97

Code

Generic B — Body

Body Control Module Communication Fault

Brand: Generic

Type: B — Body

Views: UK: 6 EN: 6 RU: 6

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Completed

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Page language: EN

Causes

Faulty or intermittent BCM power or ground
Damaged, corroded, or loose connector at the BCM
Open, shorted, or high-resistance CAN/LIN bus wiring
Missing or failed bus termination resistor(s)
Network interference or excessive bus errors (bus-off)
Faulty BCM internal electronics or failed firmware

Symptoms

Multiple modules show loss-of-communication warnings or malfunction
Interior electrical features (lights, locks, windows) erratic or inoperative
Instrument cluster messages about network faults or module missing
Intermittent or permanent stored communication-related DTCs
Vehicle may enter limp-home or prevent start depending on network role

What to check

Read all stored and pending DTCs on all modules; note freeze-frame and timestamp
Verify battery voltage and charge state; perform load test if required
Visually inspect BCM connector and adjacent wiring for corrosion, bent pins, or water intrusion
Scan for CAN/LIN bus errors and module presence using a capable diagnostic tool
Measure CAN_H/CAN_L (and LIN if present) idle voltages and compare to spec
Check for proper bus termination (approx. 60 ohms across CAN_H and CAN_L with key off)

Signal parameters

CAN bus idle voltage levels on CAN_H and CAN_L
Dominant (bus active) voltage levels and transition integrity
Presence and frequency of BCM-specific CAN message IDs
Number and type of bus error frames, CAN bus-off counters
Termination resistance between CAN_H and CAN_L (approx. system spec ~60Ω)
LIN bus idle voltage and message timing if BCM uses LIN sub-net

Diagnostic algorithm

Use a full-function scan tool to record all communication-related DTCs and verify B1C97 conditions and freeze data.
Confirm stable battery voltage (12.4–12.8 V) with key on; charge or replace battery if low.
Inspect BCM connector, harness, and nearby grounds for corrosion, damaged wires, or water intrusion; repair as needed.
With ignition on, monitor network traffic: verify BCM message IDs appear and message frequency matches factory spec; note absence or corruption of messages.
Measure CAN_H/CAN_L idle voltages and check termination resistance across the bus; if out of spec, trace wiring for opens/shorts or missing terminator.
Perform wiggle testing while monitoring messages to isolate intermittent wiring or connector faults.
If wiring and power/ground check good, check for other modules causing bus errors by disconnecting suspect nodes (one at a time) and observing bus recovery.
If wiring and other modules are ruled out, verify BCM software/firmware calibration and update or re-flash per manufacturer instructions.
As a last step, consider replacing the BCM and programming/configuring the new module to vehicle specifications; verify and clear codes, then road test to confirm repair.
Document findings and retest network for stability before returning vehicle to service.

Likely causes

Bad BCM ground or low battery voltage during communication
Corroded multi-pin connector at BCM or splice causing intermittent pins
Broken CAN_H/CAN_L pair or short to battery/chassis
CAN bus off condition caused by a shorted node or missing termination
BCM corrupted or incompatible software after module replacement

Fault status

⚠️ Status

Body Control Module Communication Fault — BCM messages not present or invalid on vehicle network. Could be caused by power/ground issues, wiring/connectors, bus termination problems, other modules injecting errors, or a faulty BCM. Further diagnostics required.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-4 hours