Skip to content
Tahoe / Yukon Service Manual

DTC B13AA (UE1)

Cellular, Entertainment, and Navigation | Diagnostic Information and Procedures | Document ID: 5191810 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 B13AA Cell/Global Positioning System Combined Antenna Coaxial Signal For Symptom Byte information refer to: Symptom Byte List Diagnostic Fault Information

Circuit Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
Antenna Coax Cable Cell/GPS B13AA 11 B13AA 13 B13AA 12 —

Circuit/System Description The K73 Telematic Control Module receives information from the Cellular/GPS antenna element which is part of the T4P High Frequency Antenna located on the outside of the vehicle. The Cellular/GPS antenna element is connected to the K73 Telematic Control Module via a shielded coaxial cable. The K73 Telematic Control Module supplies 5 V through the coax cable to power the internal antenna amplifier. Conditions for Running the DTC Vehicle in Service Mode. System voltage is between 9.5 V and 15.5 V. The above conditions are present for greater than 1 second. Conditions for Setting the DTC B13AA 11 The K73 Telematic Control Module detects a short to ground on the Cellular/GPS antenna signal circuit. B13AA 12 The K73 Telematic Control Module detects a short to battery on the Cellular/GPS antenna signal circuit. B13AA 13 The K73 Telematic Control Module detects an open/high resistance on the Cellular/GPS antenna signal circuit. Action Taken When the DTC Sets The OnStar® status LED turns red. The OnStar® Call Center cannot locate the vehicle. Conditions for Clearing the DTC The K73 Telematic Control Module detects the presence of a GPS antenna. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred. Reference Information Schematic Reference OnStar/Telematics 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-49903 GM OnStar Antenna Diagnostic Tool Kit Circuit/System Testing

  1. Vehicle off, disconnect the GPS coax cable connector at the K73 Telematic Control Module.
  2. Attach both leads of the EL-49903–1 OnStar test antenna to the EL-49903–5 combiner. Using the EL-49903–6 coax cable attach the grey connector to the combiner and the brown connector to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON.
  3. Verify DTC B13AA is not set or that the OnStar advisor can locate the vehicle. ⇒ If DTC B13AA is set or the advisor can not locate the vehicle Replace the K73 Telematic Control Module. ⇓ If DTC B13AA is not set or that the OnStar advisor can locate the vehicle.
  4. Vehicle off, disconnect the EL-49903-1 OnStar Test Antenna, Navn-Cell Comn from the K73 Telematic Control Module.
  5. Disconnect the GPS coax cable at the T4P High Frequency Antenna.
  6. Test the coax cable between the K73 Telematic Control Module and the T4P High Frequency Antenna. Refer to component testing. ⇒ If the coax cable does not pass the test Replace the coax cable. ⇓ If the coax cable passes the test
  7. Test or replace the T4P High Frequency Antenna. 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 diagnostic procedure. High Frequency Antenna Replacement For control module replacement, programming, and setup refer to: Control Module References for control module replacement, programming and setup.