B142C — Body Control Module — Internal Data Error

Causes

• Corrupted BCM software or calibration data
• Intermittent or low power supply to BCM (battery/charging issues)
• Poor ground or loose/corroded BCM connector pins
• Water ingress or physical damage to BCM
• Wiring harness short, open or high resistance on power/ground or communication lines
• Electromagnetic interference or external modules sending malformed messages

Symptoms

• BCM-related functions work intermittently or not at all (door locks, interior lighting, wipers, power windows, etc.)
• Instrument cluster or message center may show warnings or incorrect messages
• Vehicle may not recognize keys or have central locking anomalies
• Loss of communication with BCM reported by diagnostic tool
• Random or recurring B142C code even after clearing

What to check

• Read and record all stored DTCs and freeze frame data from BCM and other modules
• Verify vehicle battery state-of-charge and charging system (measure resting and cranking voltages)
• Visually inspect BCM connector and wiring for corrosion, pin damage, contamination or water ingress
• Check BCM supply fuse(s) and ground connections for tightness and continuity
• Use a scan tool to confirm whether the BCM is responding and whether other modules report CAN communications problems
• Note whether the code is permanent or clears and returns after ignition cycles or driving

Signal parameters

• Battery voltage: nominal 12.4–12.8 V resting, >13.5 V with engine running (approx.)
• CAN bus idle voltages: CAN_H ≈ 2.5–3.5 V, CAN_L ≈ 0.5–1.5 V; differential ~2 V when dominant
• Expected message frequency for BCM broadcast messages (varies by model) — check OEM data for IDs and intervals
• Bus error/frame error counts: should be near zero; look for rising CRC/checksum error counters
• Module supply and ground resistance: near 0 Ω to chassis ground; traces >0.5 Ω indicate problem
• Internal diagnostic status flags/checksum fields (as reported by OEM tool)

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