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 shielded coaxial cable. The antenna cable also provides a path for DC current for powering the cellular antenna.


Conditions for Running the DTC

* Radio ON.
* Battery voltage must be between 9-16 volts.



Conditions for Setting the DTC

The DTC will set when the VCIM detects a short to ground or an open/high resistance in the cellular antenna signal circuit.


Action Taken When the DTC Sets

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



Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.



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


Component Testing

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



1. Ignition OFF, disconnect the coax harness connectors at the VCIM and the cellular antenna.
2. Test for less than 5 ohms between the two ends of the coax cable center conductor.

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

3. Test for less than 5 ohms between the two ends of the coax cable outer shield.

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

4. Test for infinite resistance between the coax center conductor and the outer shield.

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

5. Connect the coax harness connector at the VCIM.
6. Ignition ON, test for 4.0-5.5 volts between the coax center conductor and the outer shield.

• If not within the specified range, replace the VCIM.

7. If all circuits test normal, 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