Chevrolet Trax: No global positioning system (GPS) reception

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.

Circuit/System Description

The navigation antenna is connected to the Telematics Communication Interface Control Module. The module supplies 5 V to the antenna to power the internal amplifier through the center conductor of the antenna coax cable.

When the vehicle is equipped with the optional navigation radio, a Navigation Antenna Signal Splitter is installed to distribute the navigation signal to both the Telematics Communication Interface Control Module and the navigation radio. The Telematics Communication Interface Control Module supplies 5 V through the coax cable to power the internal antenna amplifier through the signal splitter.

Diagnostic Aids

• The scan tool Telematics Communication Interface Control Module GPS signal parameter will display a Yes or No dependent upon whether or not the module sees an increment of the seconds transmitted by GPS signals to the Telematics Communication Interface Control Module. Upon entering this screen, the GPS signal title will initially display Yes, regardless of the presence of time increment, for at least 2 seconds, while the algorithm in the scan tool determines the status of the clock. If increment is found, Yes is continually displayed. If the clock remains static, No is displayed. The scan tool looks for increment every second, regardless of current display.
• 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 cellular phone and navigation antenna from a clear view of the satellites in the sky and may have caused this temporary data loss.
• The 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

• OnStar/Telematics Schematics (Encore), OnStar/Telematics Schematics (Trax)
• Radio/Navigation System Schematics (Encore), Radio/Navigation System Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

• OnStar Description and Operation
• Radio/Audio System Description and Operation (with Monochrome Display), Radio/Audio System Description and Operation (with Color Display)

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 OnStar Antenna 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 the ignition ON for the vehicle to acquire the GPS satellites signal.

1. Ignition ON.
2. Verify that no DTCs are set.

If any DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

If no DTCs are set

3. Verify that an OnStar advisor can locate the vehicle after performing a blue button press.

• If the advisor can not locate the vehicle and the vehicle is not equipped with a navigation radio

Refer to Circuit System Testing Without Navigation Radio.

• If the advisor can not locate the vehicle and the vehicle is equipped with a navigation radio
• Refer to Circuit System Testing With Navigation Radio.
• If the advisor can locate the vehicle

4. Verify that the NO GPS symbol/message is not displayed on the radio.

• If the NO GPS symbol/message is displayed

Refer to Circuit System Testing With Navigation Radio- Step 9.

• If the NO GPS symbol/message is not displayed

5. All OK.

Circuit/System Testing

without Navigation Radio

1. Ignition OFF, disconnect the GPS and cellular coax cable connector at the K73 Telematics Communication Interface Control Module.
2. Using the EL-49903 OnStar Antenna Diagnostic Tool Kit , connect the EL-49903-3 antenna to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON.
3. Verify that an OnStar advisor can locate the vehicle after performing a blue button press.

• If the advisor can not locate the vehicle

Replace the K73 Telematics Communication Interface Control Module.

• If the advisor can locate the vehicle

4. Test the coax cable between the K73 Telematics Communication Interface Control Module and the T4G Cellular Phone, Navigation, and Digital Radio 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

5. Test or replace the T4G Cellular Phone, Navigation, and Digital Radio Antenna.

with Navigation Radio

NOTE: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the T4G Cellular Phone, Navigation, and Digital Radio Antenna coax cable at the T15 Navigation Antenna Signal Splitter.
2. Using the EL-49903 OnStar Antenna Diagnostic Tool Kit , connect the EL-49903-3 antenna to the T15 Navigation Antenna Signal Splitter. Place the test antenna on the roof of the vehicle, ignition ON.
3. Verify that an OnStar advisor can not locate the vehicle after performing a blue button press.

If the advisor can locate the vehicle

1. Test the coax cable between the T15 Navigation Antenna Signal Splitter and the T4G Cellular Phone, Navigation, and Digital Radio 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

2. Replace the T4G cellular phone, navigation and digital radio antenna.

If the advisor can not locate the vehicle

4. Ignition OFF, disconnect the GPS and cellular coax cable connector at the K73 Telematics Communication Interface Control Module.
5. Using the EL-49903 OnStar Antenna Diagnostic Tool Kit , connect the EL-49903-3 antenna to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON.
6. Verify that an OnStar advisor can locate the vehicle after performing a blue button press.

• If the advisor can not locate the vehicle.

Replace the K73 Telematics Communication Interface Control Module.

• If the advisor can locate the vehicle.

7. Ignition OFF.
8. Test the coax cable between the T15 Navigation Antenna Signal Splitter and the K73 Telematics Communication Interface Control Module. Refer to Component Testing.

• If the coax cable does not pass the test.

Replace the coax cable.

• If the coax cable passes the test.

9. Ignition OFF, disconnect the GPS coax cable at the A11 Radio.
10. Connect the EL-49903 OnStar Antenna Diagnostic Tool Kit to the A11 Radio and place the test antenna on the roof of the vehicle.
11. Ignition ON.
12. Verify that the NO GPS symbol/message is not displayed on the A11 Radio.

• If the NO GPS symbol/message is displayed

Replace the A11 Radio

• If the NO GPS symbol/message is not displayed.

13. Ignition OFF.
14. Test the coax cable between the T15 Navigation Antenna Signal Splitter and the A11 Radio. Refer to Component Testing.

• If the coax cable does not pass the test.

Replace the coax cable.

• If the coax cable passes the test.

15. Test or replace the T15 Navigation Antenna Signal Splitter.

Component Testing

CAUTION: Refer to Test Probe Caution .

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 center coax terminals, use care not to ground the test probe on the outer housing/shield.
• The vehicle may be equipped with sectioned coax. Test each section and replace only the faulty section, not the entire length of coax.

Coax Cable Test

1. Ignition OFF, disconnect the coax cable at both components.
2. Test for less than 5 ohms between the coax cable center terminal end to end.

• If 5 ohms or greater

Replace the coax cable.

• If less than 5 ohms

3. Test for greater than 5 ohms between the coax cable outer shield end to end.

• If 5 ohms or greater

Replace the coax cable.

• If less than 5 ohms

4. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield.

• If less than infinite resistance

Replace the coax cable.

• If infinite resistance

5. 5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Radio Antenna Base Replacement
• Control Module References for radio or telematics communication interface control module replacement, programming, and setup.

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