No Global Positioning System (GPS) Reception (without UE1)

Cellular, Entertainment, and Navigation | Diagnostic Information and Procedures | Document ID: 5367186 No Global Positioning System (GPS) Reception (without UE1) 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	1	1	—
1. Poor GPS reception

Circuit/System Description The A11 Radio 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 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 ON for greater than 5 s. System voltage is between 9 V and 16 V. Conditions for Setting the DTC B13AA 11 The A11 Radio detects a short to ground on the Cellular/GPS antenna signal circuit. Conditions for Clearing the DTC The A11 Radio detects the presence of a Cellular/GPS antenna element. 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 Cell/GPS coax cable connector at the A11 Radio.
2. Connect the EL-49903-1 OnStar Test Antenna, Navn-Cell Comn to the A11 Radio. Place the test antenna on the roof of the vehicle, ignition ON.
3. Verify DTC B13AA is not set. ⇒ If DTC B13AA is set. Replace the A11 Radio. ⇓ If DTC B13AA is not set.
4. Vehicle OFF, disconnect the EL-49903-1 OnStar Test Antenna, Navn-Cell Comn from the A11 Radio.
5. Disconnect the Cell/GPS coax cable at the T4P High Frequency Antenna.
6. Test the coax cable between the A11 Radio 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. Replace the T4P High Frequency Antenna. Component Testing

Note

Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues. Coax Cable Test

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 Communication Interface Module replacement, programming and setup.