Buick Regal: Unable to Contact OnStar Call Center

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.
• Refer to Diagnostic Procedure Instructions for an overview of each diagnostic category.

DTC Descriptors

DTC B2470 02

Cellular Phone Antenna Circuit Malfunction Short to Ground

DTC B2470 04

Cellular Phone Antenna Circuit Malfunction Open Circuit

Circuit/System Description

The primary cellular phone antenna element is connected to the telematics communication interface control module (violet connector) via a shielded coaxial cable. Cellular communication takes place on both the primary cellular antenna signal circuit and the GPS/secondary cellular antenna signal circuit.

This diagnostic only applies to the primary cellular antenna signal circuit. Internal to the antenna on the cellular antenna signal circuit resistance is used to apply a load, which the telematics communication interface control module uses to detect the presence of the antenna.

Conditions for Running the DTC

• Ignition in the RUN or ACC position.
• System voltage is between 9.5 V and 15.5 V.
• The above conditions are present for greater than 1 s.

Conditions for Setting the DTC

B2470 02

The telematics communication interface control module detects a short to ground on the primary cellular antenna signal circuit.

B2470 04

• The telematics communication interface control module detects an open or high resistance on the primary cellular antenna signal circuit.
• The above conditions are present for greater than 1 s.

Action Taken When the DTC Sets

The OnStar status LED turns red.

Conditions for Clearing the DTC

• The telematics communication interface control module detects the presence of a cellular antenna.
• A history DTC clears after 50 malfunction-free ignition cycles.

Reference Information

Schematic Reference

OnStar/Telematics Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

OnStar Description and Operation (UE1 with IOB/IO6) , OnStar Description and Operation (UI3) , or OnStar Description and Operation (UE1 without IOB/IO6).

Electrical Information Reference

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

Scan Tool Reference

Control Module References for scan tool information.

Special Tools

EL-49903-1 Test Antenna Navn-Cell Comn

Circuit/System Testing

NOTE:

• The vehicle may be equipped with sectioned coax. Test each section and replace only the faulty section, not the entire length of coax.
• The following verification requires the vehicle to be outside with an unobstructed view of the southern sky. Allow 5 min after turning the ignition ON for the GPS satellites to acquire vehicle signal.

1. Ignition OFF/Vehicle OFF and all vehicle systems OFF, disconnect the violet primary cellular coax cable connector at the K73 Telematics Communication Interface Control Module. It may take up to 2 min for all vehicle systems to power down.

2. Using the EL-49903-1 Test Antenna Navn-Cell Comn connect the violet coax cable to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON/vehicle in Service Mode.

3. Verify the DTC does not set or a call can be completed to the OnStar Call Center while operating the vehicle within the conditions for running the DTC.

• If the DTC sets or a call can not be completed to the OnStar Call Center

Replace the K73 Telematics Communications Interface Control Module.

• Go to next step: If the DTC does not set or a call can be completed to the OnStar Call Center

4. Ignition OFF/Vehicle OFF.

5. Disconnect the EL-49903-1 Test Antenna Navn-Cell Comn from the K73 Telematics Communication Interface Control Module 6. Test the coax cable. Refer to Component Testing.

• If the coax cable does not pass the test

Replace the coax cable.

• Go to next step: If the coax cable passes the test

7. Test or replace the T2RR Antenna - Roof Rear.

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 readings when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.

Coax Cable Test

1. Test for less than 5 Ω between the coax cable center terminal end to end.

• If 5 Ω or greater

Replace the coax cable.

• Go to next step: If less than 5 Ω

2. Test for greater than 5 Ω between the coax cable outer shield end to end.

• If 5 Ω or greater

Replace the coax cable.

• Go to next step: If less than 5 Ω

3. 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.

• Go to next step: If infinite resistance

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

• Refer to High Frequency Antenna Replacement
• Refer to Control Module References for telematics communication interface control module replacement, setup, and programming

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