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
- 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

* Ignition in the RUN or ACC position.
* System voltage is 9.5-15.5 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)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


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

1. Disconnect the harness connector at the radio antenna.
2. Ignition OFF, test for less than 10 ohms between the terminal 3 outer shield and ground.

• If greater than the specified range, test the antenna coax shield for an open/high resistance. If the coax tests normal, replace the VCIM.

3. Ignition ON, test the terminal 3 center terminal for 0.5-1.0 volts.

• If greater than the specified range, test the antenna coax center terminal for a short to voltage. If the coax tests normal, replace the VCIM.
• If less than the specified range, test the antenna coax center terminal for a short to ground or an open/high resistance. If the coax tests normal, replace the VCIM.

4. If all circuits test normal, replace the antenna.



Repair Instructions

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

* Radio Antenna Replacement (L48) (Radio Antenna Replacement (L48))Radio Antenna Replacement (L08) (Radio Antenna Replacement (L08))
* Control Module References (Programming and Relearning) for VCIM replacement, setup, and programming