Communication Interface Module

DTC B2462 (Communication Interface Module)

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 Descriptors

DTC B2462 02
- Global Positioning System (GPS) Signal Short to Ground

DTC B2462 04
- Global Positioning System (GPS) Signal Open Circuit

Circuit/System Description

The vehicle communications interface module (VCIM) receives information from the radio antenna located on the outside of the vehicle. The radio antenna is connected to the telematics communication interface control module via a shielded coaxial cable. The antenna cable also provides a path for DC current for powering the radio antenna.

Conditions for Running the DTC

* Ignition is in the RUN or ACC position.

* System voltage is between 9.5 V and 15.5 V.

* The above conditions are present for greater than 1 second.

Conditions for Setting the DTC

B2462 02

The vehicle communications interface module detects a short to ground on the navigation antenna signal circuit.

B2462 04

The vehicle communications interface module detects an open/high resistance on the navigation antenna signal circuit.

Action Taken When the DTC Sets

* The OnStar(R) status LED turns red.

* The OnStar(R) Call Center cannot locate the vehicle.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.

* A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

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

Note: The following verification requires the vehicle to be outside with an unobstructed view of the southern sky. Allow 5 minutes after turning key on for the GPS satellites to acquire vehicle signal.

Ignition ON, wait 5 minutes, then contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call, verifying the vehicle OnStar system is functioning and the consultant can locate the vehicle.

Circuit/System Testing

1. Ignition OFF, disconnect the GPS and cell coax cable connector at the vehicle communication interface module.

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 vehicle communication interface module, place the test antenna on the roof of the vehicle.

3. Ignition ON, wait 5 minutes, then contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call, ask the consultant to verify the vehicle location to confirm the GPS system is functioning.

• If the OnStar GPS does not function, replace the vehicle communication interface module.

4. Ignition OFF, perform the coax cable test on the coax cable, refer to Component Testing. The coax cable should pass the test.

• 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.

* Radio Antenna Base Replacement Radio Antenna Base Replacement

* Control Module References Programming and Relearning for telematics communication interface control module replacement, setup, and programming