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 02
- Cellular Phone Antenna Circuit Malfunction Short to Ground

DTC B2470 04
- Cellular Phone Antenna Circuit Malfunction Open Circuit

Circuit/System Description

The radio antenna is connected to the vehicle communication interface module (VCIM) with a RG-58 coax cable. The VCIM polls the data from the radio 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 VCIM does not detect the presence of a radio 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 VCIM detects the presence of a radio 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 A/C Compressor Clutch

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 radio antenna and radio antenna coupling assembly are not damaged.

If the antenna assembly is damaged, replace the radio 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 VCIM.

2. Using the EL-49903-3 kit (EL-49903-5 adapter and EL-49903-4 coax cable), connect the EL-49903 - GM OnStar antenna diagnostic tool kit to the VCIM.

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 VCIM.

4. Ignition OFF, disconnect the EL-49903 - GM OnStar antenna diagnostic tool kit from the VCIM and perform the coax cable test on the coax cable between the VCIM and the radio antenna.

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

5. If all circuits test normal, replace the 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 ohms 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 ohms 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.

* Antenna Cable Replacement Antenna Cable Replacement

* Radio Antenna Base Replacement Radio Antenna Base Replacement

* Control Module References Programming and Relearning for VCIM replacement, setup, and programming