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Tahoe / Yukon Service Manual

Digital Radio Poor or No Reception

Cellular, Entertainment, and Navigation | Diagnostic Information and Procedures | Document ID: 5411592 Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptors DTC B174E XM Antenna Coaxial Signal For Symptom Byte information refer to: Symptom Byte List Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
Antenna Coax Cable B174E 11 B174E 13 1 —
1. Poor GPS reception

Circuit/System Description The digital radio receiver, located inside the A11 Radio, receives digital radio information from the XM antenna element which is part of the T4P High Frequency Antenna located on the outside of the vehicle. The XM antenna element is connected to the A11 Radio via a shielded coaxial cable. The A11 Radio supplies 5 V through the coax cable to power the internal antenna amplifier. Conditions for Running the DTC Ignition is in the RUN or ACC position for more than 5 s System voltage is between 9-16 V. Conditions for Setting the DTC B174E 11 Short to ground on the XM antenna signal circuit. B174E 13 Open/high resistance on the XM antenna signal circuit. Conditions for Clearing the DTC The A11 Radio detects the presence of a XM antenna. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred. Reference Information Schematic Reference Radio/Navigation System Schematics Connector End View Reference Master Electrical Component List Description and Operation OnStar Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References for scan tool information Special Tools EL-48028 Digital Radio Test Antenna. Circuit/System Verification

  1. With the vehicle outside in an area with an unobstructed view of the southern sky, tune to XM.
  2. Verify DTC B174E is not set as current and the No XM Signal message is not displayed on the A11 Radio. ⇒ If DTC B174E is set as current or the No XM Signal message is displayed. Refer to Circuit/System Testing. ⇒ If the customer complaint indicates certain XM channels are missing or certain XM channels have no audio Refer to Missing XM Channels or No Audio On Certain XM Channels ⇓ If DTC B174E is not set as current and the No XM Signal message is not displayed and all expected channels are present and functioning correctly.
  3. A fault is currently not present and may be an intermittent condition. Circuit/System Testing
  4. Ignition OFF/Vehicle OFF, disconnect the digital radio antenna coax cable from the A11 Radio. Connect the EL-48028 Digital Radio Test Antenna to the radio and place on the roof of the vehicle.
  5. Ignition ON/Vehicle in Service Mode, radio tuned to XM channel 1.
  6. Verify DTC B174E is not set as current and XM reception is improved. ⇒ If DTC B174E is set as current or XM reception is not improved Replace the A11 Radio. ⇓ If DTC B174E is not set as current and XM reception is improved
  7. Ignition OFF/Vehicle OFF, disconnect the digital radio antenna coax cable from the T4P High Frequency Antenna.
  8. Verify the digital radio antenna coax cable passes the coax cable component test. Refer to Component Testing. ⇒ If the coax cable does not pass the test Replace the antenna coax cable ⇓ If the coax cable passes the test
  9. Test or replace the T4P High Frequency Antenna. Missing XM Channels or No Audio On Certain XM Channels
  10. Locate vehicle with a clear view of the southern and western sky while channel 1 is playing audio.
  11. Record the XM Radio ID from channel 0. If there is no channel 0, the XM Radio ID can be found by tuning to the XM band then under System Settings select Manage.
  12. Call XM at US: www.xmradio.com or 1-800-556-3600 prompt 2 or Canada: 1-877-438-9677 and verify the customer’s account is properly setup for the customer and has active XM service for the vehicle. Note: For concerns with missing channels, it is necessary to verify channel status with XM (some channels may be moved or deleted by XM and some are package specific or are listed as Online listening only).
  13. Perform an Ignition/RAP Power cycle
  14. Verify that “no audio” or “missing channels” condition still exists (Review all channels and documenting those channels that are missing or have no audio).
  15. Call XM again and request the XM advisor to deactivate the service. From there, verify that the deactivation was received by the receiver by verifying they only have Channels 0 and 1 available. This process could take 5+ minutes.
  16. Perform an Ignition/RAP Power cycle (Should still see only channel 0 and channel 1 present after this power cycle).
  17. Call XM and Activate the receiver with the SiriusXM programming package appropriate for the capability of the audio system.
  18. The activation can take up to 30 minutes to complete. Do not attempt to change from channel 1 until the XM advisor says it is ok to change channels. (Note: A slight mute in the audio may be heard on some models during the activation).
  19. Once other channels appear, wait a few more minutes for all channels to load properly, then turn the radio off.
  20. Perform an Ignition/RAP Power cycle
  21. Check activation status (Proceeded with checking ALL available channels for no audio condition).
  22. Power cycle vehicle.
  23. Recheck activation status (Checked all previously suspect channels written down earlier in step 4).
  1. Ignition OFF, disconnect the coax cable at both components.
  2. Locate the appropriate pinout adaptor and load test loop adaptor from EL-52552 COAX FAKRA Cable Adaptor Kit.
  3. Connect the 2 adaptors together, test and record the resistance between the terminals at the pinout adaptor.
  4. Disconnect the 2 adaptors and connect each one to the appropriate end of the coax cable.
  5. Measure the total resistance of the coax cable loop including all connected adaptors at the pinout adaptor. ⇒ If greater than 5 Ω plus or minus the reading from step 3. Replace the coax cable ⇓ If less than 5 Ω plus or minus the reading from step 3.
  6. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the diagnostic procedure. High Frequency Antenna Replacement Control Module References for Communication Interface Module replacement, programming and setup.