Code
B3287
HUMMER
B — Body
Body Control Module Communication Bus Malfunction
Views:
UK: 13
EN: 14
RU: 8
AI status
Completed
Completed
100%
Causes
- Open or short in communication bus wiring (CAN/LIN)
- Loose, corroded or damaged BCM connector pins
- Faulty BCM hardware or internal fault
- Low battery voltage or poor battery/charging system performance
- Blown fuse or faulty power/ground to BCM
- Faulty or intermittent module on same network causing bus errors
Symptoms
- One or more body systems inoperative or intermittent (doors, locks, lighting, wipers, HVAC, remote functions)
- Multiple control modules reporting communication faults or ‘module missing’ on scan tool
- Illumination of warning lamps related to body systems
- Intermittent operation of accessories or erratic behavior of controls
- Stored DTC B3287 and possibly other U- or B- network codes
What to check
- Connect a factory-level scan tool and read all current and history codes across all networks; record freeze-frame data
- Check for additional U- and B- codes to identify affected network and possibly the offending module
- Visually inspect BCM connector and harness for corrosion, bent pins, water intrusion, or physical damage
- Verify BCM power and ground circuits with a DVOM (battery voltage present at power pins; ground near 0 ohms to chassis)
- Check fuses and fusible links related to BCM power supplies
- Measure CAN bus resistance end-to-end (~60 ohms total with both terminators in place) and inspect for shorts to battery/ground
Signal parameters
- High-speed CAN (typical factory data) — idle voltages ~2.5 V on CAN High and CAN Low; differential voltage ~0 V when recessive and ~2 V when dominant (exact values depend on vehicle)
- End-to-end CAN bus resistance with two 120 ohm terminators ≈60 ohms
- LIN and other single-wire buses idle near battery voltage and show pull-down pulses during communication — consult factory data for exact values
- Bus baud rate and message set vary by network; use factory scan/oscilloscope settings for accurate capture
Diagnostic algorithm
- Retrieve and document all DTCs from all networks; note occurrence and freeze-frame. Check for related U-codes (lost communication) to scope affected bus. 2) Verify battery state-of-charge and charging system; ensure stable supply voltage. 3) Inspect BCM connectors and harness for corrosion, moisture, damaged pins; repair as needed. 4) Verify BCM power and ground circuits: measure voltage at BCM power pins with key on and cranking; check ground continuity to chassis. 5) Inspect/verify fuses and fusible links for BCM and bus power. 6) Check CAN/LIN bus wiring for physical damage along harness routes (doors, harness entry points). 7) Measure CAN bus resistance across CANH to CANL with ignition off — expect ~60 ohms; open or very high = missing terminator, near 0 = short. 8) Use oscilloscope or a protocol-capable scan tool to view waveforms on the bus while key on/operating: look for excessive noise, dominant-stuck states, lost frames or abnormal voltages. 9) Isolate network segments by disconnecting non-essential modules one at a time (or disconnecting BCM if procedure requires) to identify the module causing the fault. 10) If wiring and power/ground are good and the bus looks correct, check for available BCM software updates or required reprogramming; follow factory reflash procedure. 11) Replace BCM only after all wiring, connectors and other modules have been ruled out; program/configure replacement as required by manufacturer. 12) Clear codes and verify repair by road test and re-scan for reappearance.
Likely causes
- Corroded or loose BCM power/ground or IV connector at BCM
- Short to battery or ground on CAN high/low or LIN conductors
- Failed termination resistor(s) on CAN bus (open/shorted 120 ohm terminators)
- Intermittent wiring damage (pinched, chafed) near doors/harness routing
- Software/firmware mismatch or need for BCM reflash after module replacement
Fault status
Status
B3287 — BCM Communication Bus Malfunction: BCM is detecting communication errors on the vehicle network. May cause multiple body systems to be inoperative or report other module communication faults.
Repair difficulty: Medium
Diagnostic time: 1.0-4.0 hours
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