Chevrolet Silverado / GMC Sierra. Service manual — part 2224

1. Ignition OFF, disconnect the GPS coaxial cable from the GPS antenna.

2. Ignition ON, test for 4.0-5.5 volts between the center conductor and the shield of the

coaxial cable.

If not within the specified range, replace the GPS antenna.

3. Ignition OFF, test for less than 5 ohms or resistance at the GPS coaxial cable center

conductor from end to end.

If greater than the specified range, replace the GPS coaxial cable.

4. Ignition OFF, test for infinite resistance between the center conductor and the outer

conductor of the GPS coaxial cable.

If less than the specified range, replace the GPS coaxial cable.

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

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Global Positioning System (GPS) Antenna Replacement

Control Module References for radio replacement, setup, and programming

DTC B2470

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B2470 00

Cellular Phone Antenna Circuit Malfunction

Circuit/System Description

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

Conditions for Running the DTC

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

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 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® Call Center.

The OnStar® status LED turns red.

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.

Reference Information

Schematic Reference

OnStar Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Scan Tool Reference

Control Module References for scan tool information

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.

Component Testing

1. Disconnect the cellular antenna coax connector from the VCIM and the cellular antenna.

2. Test for infinite resistance between the center conductor and the outer metal shield of the

cellular antenna coax cable.

If meter does not read infinite, replace the cellular antenna coax cable.

3. Test for less than 1 ohm of resistance at the cellular antenna coax connector from end to end.

If greater than specified value, replace the cellular antenna coax cable.

4. Ignition OFF, connect a fused jumper wire between coaxial center conductor and the metal

outer shield at the VCIM antenna coax cable connector.

5. Ignition ON, verify that DTC B2470 is not current.

If DTC B2470 is still current, replace the VCIM.

6. If all circuits test normal, replace the cellular antenna.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Mobile Telephone Digital Antenna Replacement

Control Module References for VCIM replacement, setup, and programming

DTC B2474

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

IMPORTANT: The vehicle may be equipped with sectioned coax. Test each

section and replace only the faulty section, not the entire length
of coax.

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B2474 07

Navigation Display Head Backlighting Performance

Circuit Description

The internal backlighting of the navigation display screen located in the navigation radio.

Conditions for Running the DTC

Radio ON.

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

The navigation radio tests the navigation display backlighting every 1 second.

The radio determines there is a malfunction or overheat condition in the navigation display
backlighting.

Action Taken When the DTC Sets

Navigation backlighting may be too bright, dim or blank.

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.

Diagnostic Aids

Occasionally it is possible to overheat the navigation display backlighting due to excessive
ambient heat inside the vehicle. In this instance it may be necessary to allow time for the display
to cool.

Reference Information

Schematic Reference

2008 Chevrolet Silverado 1500

2008 ACCESSORIES & EQUIPMENT Cellular, Entertainment, and Navigation - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado