Code
B2750
HUMMER
B — Body
Body Control Module Internal Fault
AI status
Completed
Completed
100%
Causes
- Internal BCM hardware failure (failed component or circuit)
- Corrupted or incomplete BCM software/calibration
- Low battery or voltage surge during programming or operation
- Poor power supply or ground to the BCM (loose, corroded, or high-resistance connection)
- Water intrusion or physical damage to BCM or connectors
- Faulty or shorted wiring to BCM power/ground circuits
Symptoms
- Multiple body electrical features inoperative or intermittent (locks, lights, wipers, interior functions)
- Warning lights or messages on dash related to body systems
- BCM not responding or appearing offline on scanner
- Erratic operation of exterior/interior lights, power windows, or door locks
- Increased battery drain or parasitic draw in some cases
- Related communications DTCs stored on other modules (CAN bus errors)
What to check
- Read and record all stored DTCs and freeze-frame data with a capable scan tool; check for related codes on other modules
- Verify vehicle battery state-of-charge and battery condition; measure resting voltage (approx. 12.4–12.8 V) and charging voltage with engine running (approx. 13.5–14.8 V)
- Inspect and verify BCM power and ground circuits: check fuses, fusible links, battery feed, and chassis/body grounds for tightness and corrosion
- Visually inspect BCM connectors and wiring for water intrusion, corrosion, bent pins, damaged insulation, or evidence of tampering/aftermarket installations
- Check vehicle CAN/LIN bus status using a scan tool: verify CAN nodes present and no bus short to battery/ground
- Perform a wiggle test of harness and connectors while monitoring BCM status with scanner to see if condition changes
Signal parameters
- Resting battery voltage: ~12.4–12.8 V (subject to battery condition)
- Charging system voltage (engine running): ~13.5–14.8 V
- Acceptable BCM supply while awake: typically 11–15 V; undervoltage or spikes indicate trouble
- Ground circuit resistance to chassis: preferably
- CAN bus idle voltages: approx. 2.5 V on CAN_H and CAN_L when measured individually (refer to OEM specs)
- Cranking voltage should not drop below ~9.5 V (severe drops can affect module operation)
Diagnostic algorithm
- Connect a OEM-capable scan tool. Retrieve and document B2750 and any additional DTCs and freeze-frame data.
- Confirm battery state-of-charge and charging system operation. If battery is weak, charge or replace before further testing.
- Visually inspect BCM and harness: look for water intrusion, corrosion, damaged pins, or aftermarket device connections. Repair as needed.
- Verify all BCM power feeds and fuses. Measure battery feed voltage at the BCM connector and compare to vehicle battery voltage.
- Verify ground integrity: measure resistance between BCM ground pins and chassis/negative battery; repair high-resistance grounds.
- Check vehicle data bus (CAN/LIN) for errors. Use scanner to confirm BCM is present on the bus and communicating. Address bus faults or other module issues first.
- Perform a wiggle test of wiring/connectors while observing scanner for changes or intermittent faults. Repair any intermittent wiring issues.
- If power/ground and communication are confirmed good and no external cause is found, check for available BCM software updates or reflash procedures per OEM service information. Follow OEM procedures for reprogramming; ensure stable battery/power during flash.
- If reflash does not clear the fault or is not possible, follow OEM diagnostics for internal module failure. Most cases require BCM replacement and programming to vehicle VIN and security parameters.
- After repair or module replacement, clear codes, re-run system tests, verify operation of affected systems, and perform a road test to confirm the fault is resolved.
Likely causes
- Corrupted module software due to interrupted reflash or weak battery during programming
- High-resistance ground or battery connection causing undervoltage
- Damaged connector pins or corrosion causing intermittent contacts
- Internal electronic component failure from heat, moisture, or age
- Electrical transient (jump start, short circuit) that damaged internal BCM circuits
Fault status
Status
Stored DTC B2750 — Body Control Module internal fault. Module self-test indicates an internal malfunction or corrupted software. Verify power, ground, connectors, and communications; update or replace and program BCM as required per service procedures.
Repair difficulty: Hard
Diagnostic time: 1.0-4.0 hours
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