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No Global Positioning System (GPS) Reception

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The navigation aerial is connected to the radio by a coax cable. The radio supplies 5 V through the centre conductor of the coax cable to power aerial.

Diagnostic Aids
    • Inaccurate or aged GPS position concerns which are no longer present may have been due to the temporary loss of GPS signal reception by the vehicle. Conditions such as tunnels or parking structures will restrict the navigation aerial from a clear view of the satellites in the sky and may have caused this temporary data loss.
    • The global positioning system (GPS) requires a clear line of sight to the sky to operate properly. In most cases the GPS will not have reception near tall buildings or inside structures.

Reference Information

Schematic Reference

Radio/Navigation System SchematicsRadio/Navigation System Schematics

Connector End View Reference

Component Connector End ViewsComponent Connector End Views

Description and Operation

Radio/Audio System Description and OperationRadio/Audio System Description and Operation

Electrical Information Reference

    • Circuit Testing Circuit Testing
    • Connector Repairs Connector Repairs
    • Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
    • Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module ReferencesControl Module References for scan tool information

Special Tools

EL-49903 EL-49903 GM OnStar Aerial Diagnostic Tool Kit

Circuit/System Verification

Note: The following verification requires the vehicle to be outside with an unobstructed view of the southern sky. Allow 5 minutes after turning key on for the GPS satellites to acquire vehicle signal.

  1. Verify the Navigation Radio functions while driving the vehicle.
    2. ⇒If the navigation radio does not function, refer to Circuit System Testing.

Circuit/System Testing
  1. Ignition OFF, disconnect the navigation aerial coax cable connector at the A11 radio.
  2. Connect the EL-49903 EL-49903 to the A11 radio, place the test aerial on the roof of the vehicle.
  3. Ignition ON, verify DTC B2462 is not set in the A11 radio.
    4. ⇒If DTC B2462 is set as current, replace the A11 radio.
  4. Ignition OFF, disconnect the aerial coax cable from the T4G mobile phone, navigation and digital radio aerial.
  5. Perform the coax cable test on the coax cable between the A11 radio and the T4G mobile phone, navigation and digital radio aerial, refer to Component Testing. The coax cable should pass the test.
    6. ⇒If the coax cable does not pass the test, replace the coax cable.
  6. Reconnect the navigation aerial coax cable connections at the A11 radio.
  7. Ignition ON, test for 4.5-5.5 V between the coax cable centre conductor and the outer shield at the T4G mobile phone, navigation and digital radio aerial.
    8. ⇒If not within the specified range, replace the the A11 radio.
  8. If all circuits test normal, replace the T4G mobile phone, navigation and digital radio aerial.

Component Testing

Caution: Refer to Test Probe Caution in the Preface section.

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.

To prevent false reading when testing the centre coax terminals, use care not to ground the test probe on the outer housing/shield.

Coax Cable Test

  1. Ignition OFF, disconnect the coax cable at both components.
  2. Test for less than 5 Ω between both ends of the coax cables centre terminals.
    3. ⇒If greater than the specified range, replace the coax cable
  3. Test for less than 5 Ω between both ends of the coax cable outer shield.
    4. ⇒If greater than the specified range, replace the coax cable
  4. Test for infinite resistance between the coax cable centre wire and the outer coax shield.
    5. ⇒If less than the specified range, replace the coax cable.

Repair Instructions

Perform the Diagnostic Repair Verification Diagnostic Repair Verification after completing the diagnostic procedure.

    • Radio Aerial Base Replacement Radio Aerial Base Replacement
    • Control Module References Control Module References for radio replacement, setup, and programming
   


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