GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The cellular portion of the cellular and navigation antenna is connected to the vehicle communication interface module (VCIM) with a RG-174 coax cable. The VCIM polls the data from the 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 1 second.

Conditions for Setting the DTC

    • The VCIM does not detect the presence of the cellular antenna.
    • All the above conditions are present for greater than 1 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 the cellular and navigation 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 checks the condition of the cellular and navigation antenna.

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

Step

Action

Value

Yes

No

Schematic Reference: OnStar Schematics

Connector End View Reference: Cellular Communication Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Inspect the cellular and navigation antenna assembly for damage.

Is the antenna assembly damaged?

--

Go to Step 7

Go to Step 3

3

Important: 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 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 and navigation antenna assembly maroon connector.
  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 ohms

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 in Wiring Systems.

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 and navigation antenna. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

7

Replace the cellular and navigation 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 Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

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