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Tahoe / Yukon Service Manual

DTC B1737

Cellular, Entertainment, and Navigation | Diagnostic Information and Procedures | Document ID: 5913336 Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC B1737 Radio Frequency Antenna Coaxial Signal Symptom Byte Information: Symptom Byte List Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
Coax Cable B1737 11 B1737 13 1 —
1. Poor AM/FM reception

Circuit/System Description The T35AF Radio Antenna Amplifier – AM/FM is enabled when the A11 Radio is turned on. The A11  Radio provides battery voltage to the T35AF Radio Antenna Amplifier – AM/FM using the center conductor of the antenna coaxial cable. When a 12 V signal is seen on the center conductor of the antenna coax, and AM/FM signals are amplified. The antenna amplifier is connected to the AM/FM antenna element which is part of the rear end spoiler. Conditions for Running the DTC Ignition On for greater than 5 s System voltage between 9–16 v Conditions for Setting the DTC B1737 11 AM/FM Antenna Signal Circuit Short to Ground B1737 13 AM/FM Antenna Signal Circuit Open Conditions for Clearing the DTC A current DTC will clear when the diagnostic runs and passes. A history DTC will clear after 100 consecutive malfunction-free ignition cycles. Diagnostic Aids Poor AM and FM radio reception may be due to multiple influences, some of which may not be vehicle related. Areas which have high RF traffic or block the signal path may cause a degradation in radio reception. Radio reception may also be influenced by items within the vehicle, but not part of the radio system. Such examples are aftermarket electrical accessories or other items which may generate noise in the vehicle electrical system. Aftermarket window tinting, especially when there is a metallic coating on the film, may reduce radio reception. Reference Information Schematic Reference Radio/Navigation System Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References Circuit/System Testing

  1. Ignition OFF, disconnect the AM/FM antenna coax cable from the A11 Radio and from the T35AF Radio Antenna Amplifier – AM/FM.
  2. Verify the 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
  3. Connect the radio antenna coax cable to the A11 Radio.
  4. Connect the appropriate pinout adaptor from EL-52552 COAX FAKRA Cable Adaptor Kit to the coax cable at the T35AF Radio Antenna Amplifier – AM/FM.
  5. Ignition ON, A11 Radio ON.
  6. Verify a test lamp illuminates between the terminals at the pinout adaptor. ⇒ If the test lamp does not illuminate Replace the A11 Radio. ⇓ If the test lamp illuminates
  7. Test or replace the T35AF Radio Antenna Amplifier – AM/FM.
  8. Verify the DTC is not set or that the radio reception is normal ⇒ If the DTC is set or the radio reception is poor. Replace the rear end spoiler which contains the T4M AM/FM antenna element. ⇓ If the DTC is not set or the radio reception is normal. A fault is currently not present and may be an intermittent condition. Component Testing
  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, measure 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. At the pinout adapter, measure the total resistance of the coax cable loop including the connected load test adaptor. ⇒ If not within 5 Ω of the reading from step 3. Replace the coax cable ⇓ If within 5 Ω of the reading from step 3.
  6. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification For control module replacement, programming, and setup refer to: Control Module References Radio Antenna Amplifier Replacement Rear End Spoiler Replacement