Code
U1176
HUMMER
U — Network/User
Loss Of RFA Communications
AI status
Completed
Completed
100%
Causes
- Blown fuse or disabled power/ground to the RFA module
- Disconnected, corroded, or damaged connectors or wiring to the RFA module
- Faulty RFA module (internal electronics or antenna)
- CAN/LAN communication bus fault (opens, shorts, high resistance, poor termination)
- Low vehicle battery or intermittent power (voltage below operating threshold)
- Software/configuration mismatch or failed module reflash
Symptoms
- Remote keyless entry, remote start or RF-based functions do not work
- Door locks/unlocks may not respond to key fob
- Instrument cluster or message center displays communication or RFA-related warnings
- Some vehicle features controlled by the RFA module may be inoperative or behave erratically
- Multiple communication-related DTCs may be present
What to check
- Scan vehicle and record current and pending DTCs from all modules; note freeze frame or time stamps
- Verify vehicle battery voltage (should be ~11.5–14.5 V with engine off/on as appropriate)
- Inspect fuses and relays for the RFA/power circuits
- Visually inspect RFA module connector(s) for corrosion, bent pins, or water intrusion
- Check for related communication codes on the CAN/LAN (scan for U0xxx codes)
- Confirm whether the RFA module is powered and awake using a diagnostic tool (module present/communicating)
Signal parameters
- RFA module supply voltage: ~11.5–14.5 V (key-off/key-on conditions vary)
- Ground continuity: near 0 ohms to chassis ground
- CAN bus idle voltage: approximately 2.5 V on CAN High and CAN Low with ~60 Ω termination between CANH and CANL
- CAN differential dominant/ recessive waveform present during communication (use a scope)
- No/low RF activity at antenna when fob used (may require specialized RF test tool)
Diagnostic algorithm
- Retrieve and record all communication-related DTCs from all modules; erase codes and attempt to reproduce U1176.
- Verify battery state-of-charge and charging system operation. Recharge or replace battery if voltage is low.
- Check and verify continuity and condition of fuses and relays supplying the RFA module; replace if faulty.
- Visually inspect and tighten the RFA module connector(s); repair damaged pins, terminals, or housing as required.
- Backprobe the RFA power and ground pins while monitoring voltage with key on; confirm stable supply and good ground.
- Use a scan tool to check whether the RFA module is present and responding on the network. If absent, check CAN wiring continuity/termination between RFA and gateway/ECM.
- Measure CANH/CANL voltages with a multimeter and view waveforms with an oscilloscope to confirm communication signals and check for bus errors or shorts.
- Inspect antenna and RF harness (if applicable) for damage and secure connections; check for excessive RF interference sources nearby.
- If wiring and vehicle network are good but the module does not communicate, check for available software updates and reprogramming procedures before module replacement.
- If all diagnostics point to module failure, replace the RFA module and reconfigure/relearn as required; clear codes and verify operation.
Likely causes
- Blown fuse or lost power/ground to the RFA module
- Damaged or loose connector at the RFA module
- CAN bus wiring open/short or loss of termination
- Faulty RFA module or antenna assembly
Fault status
Status
Loss of communications with the RFA module detected. Remote and RF-based functions may be inoperative and related systems may set communication faults.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
HUMMER
-
HUMMER: 2009
-
HUMMER: 2008
-
HUMMER: 2007
-
HUMMER: 2005
-
HUMMER: 2004
-
HUMMER: 2000
-
HUMMER: 1999
-
HUMMER: 1994
-
HUMMER: 1993
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email