Chevrolet Silverado / GMC Sierra. Manual — part 2221

1. Ignition OFF, disconnect the antenna coax from the DRR.

2. Connect the EL-48028 to the DRR and place it on the roof of the vehicle. See Special

Tools.

3. Ignition ON, radio tuned to XM, verify XM reception has improved.

If the XM reception has not improved, replace the DRR.

4. Ignition OFF, disconnect the antenna coaxial cable from the DRR antenna base.

5. Test for less than 5 ohms between the two ends of the coax cable center conductor.

If greater than the specified range, replace the antenna coax cable.

6. Test for less than 5 ohms between the two ends of the coax cable outer shield.

If greater than the specified range, replace the antenna coax able.

7. Test for infinite resistance between the antenna coax center conductor and the outer shield.

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

8. If all circuits test normal, replace the digital radio antenna.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Mobile Telephone Digital Antenna Replacement

Control Module References for DRR replacement, setup, and programming

DTC B1287

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 B1287 01

Amplifier Control Signal Circuit Short to Battery

DTC B1287 02

Amplifier Control Signal Circuit Short to Ground

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

DTC B1287 04

Amplifier Control Signal Circuit Open

Diagnostic Fault Information

Circuit/System Description

The amplifier receives PWM signals on the antenna 14V switch supply voltage circuit at varying
duty cycle percentages for controlling the ON and OFF functions of the amplifier. The radio
outputs a low duty cycle signal to produce an ON condition at the amplifier. The radio outputs a
high duty cycle signal to produce a OFF condition at the amplifier.

Conditions for Running the DTC

Radio is ON

The system voltage is at between 9 volts and 16 volts

Conditions for Setting the DTC

A short to voltage, short to ground, or an open is seen on the remote enable circuit

Action Taken When the DTC Sets

Amplifier functions are disabled

Conditions for Clearing the DTC

A current DTC clears when the condition for setting the DTC is no longer present

A history DTC clears after 100 malfunction- free ignition cycles

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

Antenna 14V Switched Supply
Voltage

B1287 02

B1287 04

B1287 01

-

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

Component Connector End Views

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Radio ON, adjust the fade and balance control to verify audio is present at each individual
channel.

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the amplifier.

2. Radio ON, test for B+ between the signal circuit terminal 8 and ground.

If less than the specified value, test the signal circuit for a short to ground or an
open/high resistance. If the circuit tests normal, replace the radio.

3. If all circuits test normal, replace the amplifier.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for radio or amplifier replacement

DTC B1288

Diagnostic Instructions

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

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 Descriptors

DTC B1288 01

Video Display Mode Control Signal Short to Battery

DTC B1288 02

Video Display Mode Control Signal Short to Ground

DTC B1288 04

Video Display Mode Control Signal Open Circuit

Diagnostic Fault Information

Circuit/System Description

The radio can control the video display mode on vehicles equipped with rear seat entertainment
(RSE) video. The radio varies a pulse with modulated (PWM) signal to the rear entertainment
video screen to command the display mode.

Conditions for Running the DTC

Ignition ON.

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

DVD Display B+

1

1

1

-

Radio ON Signal

1

1

1

-

Video Display Brightness
Signal

B1289 02

B1289 04

B1289 01

-

Video Display Mode Control

B1288 02

B1288 04

B1288 01

-

Video High Signal

1

1

1

-

Video Low Signal

1

1

1

-

DVD Display Ground

-

1

-

-

1. Video Entertainment System Inoperative.

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado