Chevrolet Silverado / GMC Sierra. Service manual — part 2226

signal terminal 11 while pressing the black phone button.

If not within the specified range, replace the inside rearview mirror.

4. Test for 2.7k-3.3k ohms between the keypad supply voltage terminal 12 and the keypad

signal terminal 11 while pressing the blue On-Star® button.

If not within the specified range, replace the inside rearview mirror.

5. Test for 11.7k-14.3k ohms between the keypad supply voltage terminal 12 and the keypad

signal terminal 11 while pressing the red emergency button.

If not within the specified range, replace the inside rearview mirror.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Inside Rearview Mirror Replacement

Control Module References for CIM replacement, setup, and programming

DTC B2483 OR B2484

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 Descriptors

DTC B2483 00

Global Positioning System (GPS) Antenna Malfunction Short to Ground

DTC B2484 00

Global Positioning System (GPS) Antenna Malfunction Open Circuit

Circuit/System Description

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

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

Conditions for Running the DTC

Ignition is in the RUN or ACC position.

Battery voltage is between 9-16 volts.

Conditions for Setting the DTC

B2483 00

The CIM detects a short to ground on the navigation antenna signal circuit.

B2484 00

The CIM detects an open/high resistance on the navigation antenna signal circuit.

Action Taken When the DTC Sets

The OnStar® status LED turns red.

The OnStar® 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

Connector End View Reference

Component Connector End Views

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Circuit/System Testing

1. Disconnect the navigation antenna coax cable from the CIM.

2. Ignition ON, test for 4.5-5.5 volts between the CIM coax cable connection center conductor

and ground.

If the reading is not within the specified range, replace the CIM.

3. Reconnect the coax cable to the CIM. Disconnect the coax cable from the navigation

antenna.

4. Test for 4.5-5.5 volts between the coax cable center conductor and the outer shield.

If the reading is not within the specified range, replace the coax cable.

5. If all circuits test normal, replace the navigation antenna.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Mobile Telephone Digital Antenna Replacement

Control Module References for CIM replacement, setup, and programming

SYMPTOMS - CELLULAR COMMUNICATION

1. Perform the Diagnostic System Check - Vehicle . Before using the Symptom Tables,

verify that all of the following are true:

There are no DTCs set.

The control module can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the system functions.

Refer to OnStar Description and Operation.

3. Perform the OnStar Symptom Diagnosis. This symptom table will enable the user to

verify the customer complaint and narrow it to its source.

Visual/Physical Inspection

IMPORTANT: The following steps must be completed before using the symptom

tables.

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

Inspect for aftermarket devices which could affect the operation of the system. Refer to
Checking Aftermarket Accessories .

Inspect the easily accessible or visible system components for obvious damage or conditions
which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to
Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the
symptom:

OnStar One or More Buttons Inoperative

OnStar Call Center Remote Function Requests Inoperative

OnStar Microphone Inoperative - Caller Cannot Be Heard

OnStar Steering Wheel Control Functions Inoperative

OnStar Button LED Inoperative

No (or Noisy) OnStar Audio

OnStar Global Positioning System (GPS) Data Not Current or Inaccurate

SYMPTOMS - ENTERTAINMENT

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the Radio/Audio system.
Refer to Checking Aftermarket Accessories .

Inspect the easily accessible or visible system components for obvious damage or conditions
which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to
Testing for Intermittent Conditions and Poor Connections .

IMPORTANT: Review the system operation in order to familiarize yourself with

the system functions. Refer to Radio/Audio System Description
and Operation.

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado