B2470

DTC B2470

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptor
DTC B2470 00
- Cellular Phone Antenna Circuit Malfunction




Circuit/System Description

The cellular antenna is connected to the vehicle communication interface module (VCIM) with a RG-58 coax cable. The VCIM polls the data from the cellular antenna once every second.


Conditions for Running the DTC

* Iignition in the RUN or ACC position.
* System voltage is between 9.5 volts and 15.5 volts.
* The above conditions are present for greater than 1 second.



Conditions for Setting the DTC

* The VCIM does not detect the presence of a cellular antenna.
* The above conditions are present for greater than 1 second.



Action Taken When the DTC Sets

* The vehicle is unable to connect to the OnStar(R) Call Center.
* The OnStar(R) status LED turns red.



Conditions for Clearing the DTC

* The VCIM detects the presence of a cellular antenna.
* A history DTC clears after 50 malfunction-free ignition cycles.



Reference Information
Schematic Reference

OnStar Schematics (OnStar Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

OnStar Description and Operation (OnStar Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)



Circuit/System Verification

Verify that the cellular antenna and cellular antenna coupling assembly are not damaged.

If the antenna assembly is damaged, replace the cellular antenna.



Circuit/System Testing

Important: The vehicle may be equipped with sectioned coax. Test each section and replace only the faulty section, not the entire length of coax.



1. Ignition OFF, disconnect the cellular antenna coax from the VCIM module and the cellular antenna.
2. Ignition ON, test for less than 1 volt between the antenna coax center terminal and ground.

• If greater than the specified range, replace the antenna coax.

3. Ignition ON, test for less than 1 volt between the antenna coax outer shield and ground.

• If greater than the specified range, replace the antenna coax.

4. Test for infinite resistance between the antenna coax center terminal and ground.

• If less than the specified value, replace the antenna coax

5. Test for infinite resistance between the antenna coax outer shield and ground.

• If less than the specified value, replace the antenna coax

6. Test for less than 5 ohms at the cellular antenna coax center terminal from end to end.

• If greater than specified value, replace the cellular antenna coax cable.

7. Test for less than 5 ohms at the cellular antenna coax outer shield from end to end.

• If greater than specified value, replace the cellular antenna coax cable.

8. Test for infinite resistance between the antenna coax center terminal and the outer shield..

• If less than specified value, replace the cellular antenna coax cable.

9. If coax cable tests normal, test or replace the cellular antenna.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Cellular Communications/Digital Radio Antenna Replacement (Cellular Communications/Digital Radio Antenna Replacement)
* Control Module References (Programming and Relearning) for VCIM replacement, setup, and programming