For 1990-2009 cars

### 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.

• | Diagnostic Procedure Instructions 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

• | The ignition must be in the RUN or ACC position.

• | The system voltage is at least 9.5 volts and no more than 15.5 volts.

• | All 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® Call Center.

• | The OnStar® 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.

• | The VCIM receives the clear DTC command from the scan tool.

### Reference Information

#### Schematic Reference

OnStar Schematics

#### Connector End View Reference

Entertainment/Communication Connector End Views

#### Description and Operation

OnStar Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### 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.

### Component 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. Disconnect the cellular antenna coax connector from the VCIM and the cellular antenna.
2. Test for infinite resistance between the center conductor and the outer metal shield of the cellular antenna coax cable.

⇒ | If meter does not read infinite, replace the cellular antenna coax cable.

3. Test for less than 1 ohm of resistance at the cellular antenna coax connector from end to end.

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

4. Ignition OFF, connect a fused jumper wire between coaxial center conductor and the metal outer shield at the VCIM antenna coax cable connector.
5. Ignition ON, verify that DTC B2470 is not current.

⇒ | If DTC B2470 is still current, replace the VCIM.

6. If all circuits test normal, replace the cellular antenna.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Cellular Communications/Digital Radio Antenna Replacement

• | Control Module References for VCIM replacement, setup, and programming