Code
B2625
HUMMER
B — Body
Body Control Module communication fault
Views:
UK: 14
EN: 14
RU: 14
AI status
Completed
Completed
100%
Causes
- Low battery voltage or poor battery connection
- Blown fuse or lost BCM power/ignition feed
- Poor or missing chassis or module ground
- Damaged or corroded BCM connector or wiring harness
- Faulty BCM or internal CAN/LIN transceiver
- Short, open, or high resistance on CAN/LIN bus (wiring or termination)
Symptoms
- Multiple body systems inoperative or behaving intermittently (locks, lights, wipers, HVAC)
- Warning lamps or message center communication warnings
- Inability to communicate with BCM using diagnostic tool
- Intermittent or permanent loss of remote/keyless functions
- Random module-related DTCs for modules dependent on BCM messages
What to check
- Verify battery state of charge and terminal connections
- Check fuses and fusible links for BCM power/ignition feeds
- Scan network — confirm BCM presence and number of modules detected
- Inspect BCM connector for corrosion, bent pins, moisture or damage
- Check BCM power and ground voltages at the module connector
- Check CAN/LIN bus wiring for continuity, shorts to ground/voltage, and proper termination resistors
Signal parameters
- CAN bus idle differential ~0 V with CANH ~2.5 V and CANL ~2.5 V (recessive)
- CAN dominant state: CANH ~3.5–4.5 V, CANL ~0.5–1.5 V (short pulses when active)
- LIN bus idle ~12 V or battery voltage depending on system (pull-down to 0 V when active)
- Bus message frequency and periodic message IDs for BCM should be present on scan tool
- Tool should detect module address and show consistent alive messages or timeouts
Diagnostic algorithm
- Record freeze frame and all stored codes. Note whether code is current or intermittent.
- Verify battery voltage (>=12.4 V at rest) and charge if necessary. Ensure good battery connections.
- Clear codes and attempt to communicate with BCM using GM Tech2/MDI or compatible scanner. Note if module responds.
- Visually inspect BCM connector and wiring for corrosion, bent pins, water, or physical damage. Repair as needed.
- Check BCM power and ground pins for proper voltage and good ground continuity to chassis. Replace or repair poor connections.
- Using a scan tool or oscilloscope, monitor CAN high/low (and LIN if used). Look for valid idle voltages, differential signals, bus traffic, and absence of constant dominant or noisy lines.
- If bus noise or faults detected, isolate sections of the bus by disconnecting modules or harness branches to locate short or failed node.
- Inspect and test termination resistors (two 60 ohm resistors in parallel = ~30 ohm total on CAN), repair if out of spec.
- Remove aftermarket accessories on the bus or in body circuits and retest communications.
- If wiring, power and grounds check good and bus traffic still missing or BCM fails to respond, consider BCM reprogram/flash update (if available) or replacement. Verify proper programming and relearn procedures after replacement.
- After repairs, clear codes and road-test to confirm the fault does not return.
Likely causes
- Corroded or loose BCM connector pins
- Faulty module ground or power feed
- Fault on CAN high/low pair (short to battery, short to ground, open)
- Failed BCM transceiver or internal electronics
- Blown fuse supplying BCM
Fault status
Status
Body Control Module communication fault — loss or corruption of BCM messages on vehicle network. Intermittent or present.
Repair difficulty: Medium
Diagnostic time: 1.5-4 hours
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