OnStar Global Positioning System (GPS) Data Not Current or Inaccurate
OnStar Global Positioning System (GPS) Data Not Current or Inaccurate
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 communication interface module (CIM) with a RG-174 coax cable. The CIM polls the data from the navigation antenna once every second.
Diagnostic Aids
* The GPS signal title on the scan tool will display a Yes or No dependant upon whether or not the module sees an increment of the seconds transmitted by GPS signals to the vehicle communication interface module. Upon entering this screen, the GPS signal title will automatically 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 driving through tunnels or parking structures while making an OnStar(R) keypress will restrict the navigation antenna from a clear view of the satellites in the sky and may have caused this temporary data loss.
Circuit/System Verification
Important: It is important to have the vehicle in an open outside area where a cellular call can be successfully placed and GPS data can be received from the satellites. It is also necessary to inform the OnStar(R) Call Center advisor that this call is for vehicle diagnostic purposes.
1. Ignition ON, observe the GPS signal status indicator for at least 10 seconds with a scan tool. The indicator should display Yes.
• If the indicator does not display Yes, refer to Circuit/System Testing.
2. Call and verify the OnStar advisor has received the GPS data.
• If the advisor did not receive the GPS data and the call was a 'fail to voice', contact the GM Technical Assistance Center.
• If the advisor did not receive the GPS data and the call was not a 'fail to voice", refer to Circuit/System Testing.
3. Verify with the OnStar Call Center advisor that your actual position is within a reasonable distance from the actual location of the vehicle.
• If your actual position is not within a reasonable distance from the actual location of the vehicle, replace the CIM.
Circuit/System Testing
1. Disconnect the navigation antenna coax cable from the CIM.
2. Ignition ON, test for 4.5-5.5 volts between the CIM coax cable connection center conductor and ground.
• If the reading is not within the specified range, replace the CIM.
3. Reconnect the coax cable to the CIM. Disconnect the coax cable from the navigation antenna.
4. Test for 4.5-5.5 volts between the coax cable center conductor and the outer shield.
• If the reading is not within the specified range, replace the coax cable.
5. If all circuits test normal, replace the navigation antenna.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Cellular Communications/Digital Radio Antenna Replacement