B2470

DTC B2470

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC B2470 04
- Cellular Phone Antenna Circuit Malfunction Open Circuit

Circuit/System Description

The cellular antenna is connected to the telematics communication interface control module with a RG-58 coax cable. The telematics communication interface control module 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 between 9.5 volts and 15.5 volts.
* The above conditions are present for greater than 1 second.

Conditions for Setting the DTC

* The telematics communication interface control module 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 telematics communication interface control module 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 End Views By Name)
Description and Operation

OnStar Description and Operation (OnStar)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing For Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

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

EL-49903 GM OnStar Antenna Diagnostic Tool Kit

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

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

1. Ignition OFF, disconnect the GPS and cellular coax cable connector at the K73 telematics communication interface control module.
2. Using the EL-49903-5 adapter with EL-49903-4 coax cable, connect the EL-49903 to the K73 telematics communication interface control module.
3. Clear the DTCs and operate the vehicle within the conditions for running the DTC. Verify DTC B2470 does not set.

• If the DTC sets, replace the K73 telematics communication interface control module.

4. Ignition OFF, disconnect the EL-49903 from the K73 telematics communication interface control module and perform the coax cable test on the coax cable between the K73 telematics communication interface control module and the T4D cellular phone and digital radio antenna.

• If the coax cable does not pass the test, replace the coax cable.

5. If all circuits test normal, replace the T4D cellular phone and digital radio antenna.

Component Testing

Caution: Refer to Test Probe Caution (Test Probe Caution)

Note: Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues.

To prevent false reading when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.

Coax Cable Test
1. Ignition OFF, disconnect the GPS and cellular phone coax cable at both components.
2. Test both for less than 5 ohm between both ends of the coax cables center terminals.

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

3. Test for greater than 10k ohm between the coax cable center wire and the outer coax shield.

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

Repair Instructions

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

* Radio Antenna Base Replacement (Radio Antenna Base Replacement)
* Control Module References (Programming and Relearning)for K73 telematics communication interface control module replacement, setup, and programming