B3100

Code

Generic B — Body

Body Control Module Internal Fault

Brand: Generic

Type: B — Body

Views: UK: 13 EN: 17 RU: 15

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Page language: EN

Multiple body systems inoperative or intermittent (lights, wipers, windows, locks)
Dashboard warning for BCM or communication faults (CAN/LIN)
Inability to arm/disarm doors or remote functions
Erratic or no communication from BCM on the network (scan tool shows no response)
Modules reporting lost communications or diagnostics unrelated to actual system failures

Connect a capable scan tool and retrieve all BCM and network codes; save freeze-frame and event data
Check battery state of charge and system voltage (key on and cranking) — should be ~12.6 V at rest, 13.5–14.8 V charging
Inspect BCM fuses and fusible links for continuity
Visually inspect BCM connectors and harness for corrosion, bent pins, water damage, or burned wiring
Verify solid ground(s) at the BCM — measure resistance to battery negative (
Check CAN/LIN bus activity with a scope or tool; verify correct idle voltages and message traffic

Battery voltage (key off, key on, engine running) — expect ~12.4–12.8 V resting, ~13.5–14.8 V charging
BCM supply rail voltage at module connector (pin-specific) — should match battery/ignition rail within 0.5 V
Ground resistance from BCM to battery negative — target
CAN High/Low idle voltages ~2.5 V common-mode, ~2.5 V and ~1.5 V differential behavior; active bus waveforms present
LIN bus voltage levels and wake/sleep messages (if applicable)
Module wake/sleep/ignition status input logic levels per wiring diagram

Read and record all DTCs from BCM and other modules; note occurrence counts and freeze-frame data.
Verify battery state and charging system health; charge or replace battery if below specification.
Inspect BCM fuses, power inputs and grounds; repair any open/poor connections and re-test codes.
Visually inspect BCM enclosure and connector for moisture, corrosion, or physical damage; dry and clean as needed.
Verify module power rail voltages and ground continuity at the module connector with key on/off; repair wiring/connector faults.
Check network communications: verify CAN/LIN bus activity, proper voltages, and that the BCM appears on the bus. Repair bus wiring or terminating resistors if needed.
If wiring and power/ground are good and communications are present, attempt a software read of BCM info (part number, software level) and compare to current TSB/updates.
Clear codes and attempt to re-create the failure. If intermittent, perform wiggle testing of harness and monitor live data for faults.
If software corruption suspected, reflash or update BCM software per manufacturer procedure and re-test.
If reflash fails, errors persist, or internal hardware faults are confirmed, consult OEM guidance for module repair versus replacement and ensure proper programming/vehicle configuration after replacement.
Document all findings; if replacing BCM, follow security/anti-theft pairing and calibration procedures exactly.