GM Service Manual Online
For 1990-2009 cars only

Circuit Description

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

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2470 Cellular Phone Antenna Circuit

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 one second.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

    • The OnStar® status LED turns RED.
    • The vehicle is unable to connect to the OnStar® Call Center.

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.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests the condition of the cellular antenna.

  2. This step tests the condition of the cellular antenna coax and for proper ground of the cellular antenna.

Step

Action

Values

Yes

No

Schematic Reference: OnStar Schematics

Connector End View Reference: Entertainment/Communication Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Inspect the cellular antenna and cellular antenna coupling assembly for damage.

Is the antenna assembly damaged?

--

Go to Step 7

Go to Step 3

3

  1. Disconnect the cellular antenna coax from the vehicle communication interface module (VCIM).
  2. Measure the resistance between the center conductor and the outer metal shield.

Does the meter read out of limits?

--

Go to Step 4

Go to Step 5

4

  1. Disconnect the cellular antenna coax from the cellular antenna coupling assembly.
  2. Measure the resistance of the cellular antenna coax center conductor from end to end.

Does the resistance measure greater than the specified value?

1 Ω

Go to Step 8

Go to Step 6

5

Inspect for poor connections at the harness connector of the VCIM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

6

Inspect for poor connections at the harness connector of the cellular antenna. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

7

Replace the cellular antenna. Refer to Cellular and Navigation Antenna Assembly Replacement .

Did you complete the replacement?

--

Go to Step 10

--

8

Replace the cellular antenna coax.

Did you complete the replacement?

--

Go to Step 10

--

9

Replace the VCIM. Refer to Communication Interface Module Replacement .

Did you complete the replacement?

--

Go to Step 10

--

10

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK