Unable to Contact OnStar Call Center
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Unable to Contact OnStar Call Center
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Circuit/System Description
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The telematics communication interface control module is a cellular device that allows the user to communicate data and voice signals over the national cellular network. When an OnStar keypress is made, the telematics communication interface control module activates and connects the system to the cellular carriers communication system by interacting with the national cellular infrastructure. The module sends and receives all cellular communications over the cellular phone and navigation antenna and cellular antenna coax.
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The customer concern may have been due to a lack of cellular service in a given area. A failure in the National Cellular Network infrastructure at the time of the customers failed connection that has since been repaired may also have been the cause.
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If an OnStar® emergency call is able to successfully connect the vehicle to the OnStar® Call Center when an OnStar® Call Center button press is not, there may be a failure in the ability of the OnStar® system in the vehicle to be recognized by the local cellular carrier.
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If the prompt "OnStar® request ended" is heard, without pressing the white dot button at the end of the OnStar® keypress, the OnStar® system at one time has made a successful cellular connection, but was unable to complete the call.
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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 satellites.
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Schematic Reference
OnStar Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
OnStar Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References
for scan tool information
Special Tools
EL-49903 GM OnStar Antenna Diagnostic Tool Kit
Circuit/System Verification
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Note
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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.
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Ignition ON, wait 5 minutes, then contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call, verifying the vehicle OnStar system is functioning and the consultant can locate the vehicle.
Circuit/System Testing (without Navigation Radio)
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Note
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The vehicle may be equipped with sectioned coax. Test each section and replace only the faulty section, not the entire length of coax.
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1.
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Ignition OFF, disconnect the GPS and cellular coax cable connector at the K73 telematics communication interface control module.
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2.
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Using the EL-49903-3 kit (EL-499035 adapter and EL-49903-4 coax cable), connect the EL-49903 to the K73 telematics communication interface control module.
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3.
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Ignition ON, wait 5 minutes, and then contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call.
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4.
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If the unit does not connect to the OnStar Call Center, replace the K73 telematics communication interface module.
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5.
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Ignition OFF, disconnect the EL-49903 from the K73 telematics communication interface control module and perform the coax cable test on the coax cable between the K73 telematics communication interface control module and the T4G cellular phone, navigation, and digital radio antenna.
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6.
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If the coax cable does not pass the test, replace the coax cable.
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7.
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If all circuits test normal, replace the T4G cellular phone and navigation antenna.
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Circuit/System Testing (with Navigation Radio)
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Note
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The vehicle may be equipped with sectioned coax. Test each section and replace only the faulty section, not the entire length of coax.
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1.
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Ignition OFF, disconnect the GPS and cellular coax cable connector at the K73 telematics communication interface control module.
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2.
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Using the EL-49903-3 kit (EL-49903-5 adapter and EL-49903-4 coax cable), connect the EL-49903 to the K73 telematics communication interface control module.
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3.
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Ignition ON, wait 5 minutes, and then contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call.
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4.
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If the unit does not connect to the OnStar Call Center, replace the K73 telematics communication interface module.
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5.
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Ignition OFF, disconnect the EL-49903 from the K73 telematics communication interface control module and perform the coax cable test on the coax cable between the K73 telematics communication interface control module and the T15 navigation antenna signal splitter.
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6.
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If the coax cable does not pass the test, replace the coax cable.
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7.
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Perform the coax cable test on the coax cable between the T15 navigation antenna signal splitter and the T4G cellular phone, navigation, and digital radio antenna.
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8.
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If the coax cable does not pass the test, replace the coax cable.
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9.
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If all coax cables pass the test, replace the T15 navigation antenna signal splitter, wait 5 minutes, and then contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call.
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10.
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If the unit does not connect to the OnStar Call Center, replace the T4G cellular phone, navigation, and digital radio antenna.
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Refer to
Test Probe Caution
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Note
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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.
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To prevent false reading when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.
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Coax Cable Test
1.
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Ignition OFF, disconnect the GPS and cellular phone coax cable at both components.
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2.
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Test both for less than 5 Ω between both ends of the coax cables center terminals.
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3.
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If greater than the specified range, replace the failed coax cable.
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4.
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Test for greater than 10k Ω between the coax cable center wire and the outer coax shield.
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5.
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If less than the specified range, replace the coax cable.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.