Code
B3108
HUMMER
B — Body
Keyless Entry Receiver Fault
Views:
UK: 14
EN: 26
RU: 17
AI status
Completed
Completed
100%
Causes
- Dead or weak key fob battery
- Damaged or disconnected receiver module or antenna
- Blown fuse or poor power/ground to the receiver
- Corroded or damaged wiring/connectors between BCM and receiver
- Receiver internal failure (water damage, component fault)
- Loss of communication on vehicle data bus (CAN/LIN) to BCM
Symptoms
- Keyless entry (lock/unlock, remote start, panic) does not work or works intermittently
- No response from key fob or reduced effective range
- Malfunction indicator related to body electronics (BCM) or security
- Possible entry/lock/unlock delays or unexpected lock/unlock behavior
- Associated DTCs indicating communication faults
What to check
- Verify the code with a scan tool; record freeze frame and related codes
- Check key fob operation (replace battery and retest with known-good key fob if available)
- Inspect fuse(s) and relay(s) for receiver/BCM circuits
- Visually inspect receiver module and antenna for damage, water intrusion, or disconnected connectors
- Check for corrosion or bent pins in connectors and repair as needed
- Verify that the BCM/receiver have proper battery voltage (approx. 11–14 V) and good ground
Signal parameters
- Supply voltage to receiver: ~11–14 V with key off/crank conditions stable
- Ground: continuity to chassis ground, near 0 ohms
- RF receive frequency (vehicle dependent): commonly 315 MHz (North America) or 433.92 MHz (other regions) from the key fob
- Data bus: CAN or LIN messaging between receiver and BCM — messages present when scanning (no timeout)
- Receiver module test mode (if supported): should show valid received packet counts when pressing key fob
Diagnostic algorithm
- Connect a professional scan tool and read B3108 and any related DTCs. Record conditions and freeze-frame data.
- Verify key fob function: replace key fob battery and retest; confirm other key fobs (if available) operate correctly.
- Check fuses and relays for the receiver/BCM circuits; replace any blown fuses and retest.
- Inspect receiver and antenna location for water, damage, or disconnected connectors. Repair or reseat connectors.
- Measure supply voltage and ground at the receiver connector with ignition on; repair wiring if voltage is out of range or ground is poor.
- Check continuity of the antenna feed and inspect for corrosion or broken wires. Replace antenna/lead if open or shorted.
- Use a scan tool to monitor receiver/BCM communication while pressing the key fob. Look for received packet counts or messages; note any timeouts or errors.
- If intermittent, perform a wiggle test on harness and connectors while observing live data for changes.
- Clear codes and attempt a functional test (lock/unlock, remote start if equipped). If code returns, proceed to module-level testing.
- If wiring and power/ground are good but the receiver still fails, replace the receiver module. Follow manufacturer procedure for module replacement and perform any required programming/BCM reflash.
- After repair or replacement, clear codes and verify proper operation over a test drive and repeated remote operations.
Likely causes
- Key fob battery depleted or key fob not transmitting
- Receiver module antenna harness damaged or disconnected
- Poor power/ground at receiver (blown fuse, loose ground)
- Receiver module internal failure
Fault status
Status
Receiver not responding or reporting invalid signals to BCM; keyless entry functions may be inoperative or intermittent.
Repair difficulty: Medium
Diagnostic time: 0.5-2 hours
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