Chevrolet Silverado / GMC Sierra. Service manual — part 2236

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 Testing

Antenna Coaxial Cable Testing

1. The antenna coax may have one or two sections between the radio and the mast antenna.

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

2. Test for infinite resistance between the antenna coax center terminal and ground.

If less than the specified value, replace the antenna coax.

3. Test for less than 5 ohms of resistance on the antenna coax center terminal from end to end.

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

4. Test for less than 5 ohms of resistance on the antenna coax outer shield from end to end.

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

5. Test for infinite resistance between the coax center terminal and the outer shield.

If less than the specified value, replace the antenna coax.

Rear Glass Antenna Inspection

1. Ignition OFF, disconnect the coax from the antenna located at the rear glass.

IMPORTANT: For steps 2 - 6, perform the tests on each of the

disconnected coax cables.

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2. Verify the coax connector at the back glass is properly secured and free of any damage.

If damage is found, repair or replace as necessary.

3. Inspect the antenna on the rear glass. Verify all branches of the antenna are intact, with no

scratches or other damage.

If damage is found, repair or replace as necessary.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Radio Antenna Replacement

Control Module References for radio replacement, setup, and programming

RADIO SETUP

Radio setup is completed using Service Programming System (SPS). Refer to Service
Programming System (SPS) .

SPEAKER REPLACEMENT REFERENCE

SPEAKER MALFUNCTION

Diagnostic Instructions

Component

Repair Instruction

Front Floor Console Speaker

Refer to Radio Front Floor Console
Speaker Replacement

Front Speakers

Refer to Radio Front Speaker
Replacement

Front Door Speakers

Refer to Radio Front Side Door Speaker
Replacement

Front Pillar Speakers

Refer to Front Upper Speaker
Replacement

Rear Pillar Speakers

Refer to Rear Pillar Speaker Replacement

Rear Door Speakers

Refer to Radio Rear Side Door Speaker
Replacement (Crew Cab) or Radio Rear
Side Door Speaker Replacement
(Extended Cab)

2008 Chevrolet Silverado 1500

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

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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 provide an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

The up-level radio (UQA) supplies 4 channels of audio to an amplifier. The amplifier supplies 6
input signal channels to 8 speakers.

Each of the audio output channel circuits (+) and (-), at the radio and at the amplifier (if
equipped) have a DC bias voltage that is one half of the battery voltage. When using a DMM,
each of the audio output channel circuits will measure approximately 6.5V DC. The audio being
played on the system is produced by a varying AC voltage that is centered around the DC bias
voltage on the same circuit. The AC voltage is what causes the speaker cone to move and produce
sound. This voltage will vary depending on what type of audio is being listened to, talk or music,

Circuit

Short to

Ground

Open/High

Resistance

Short to

Voltage

Signal

Performance

Left Front Speaker Signal
Circuits (Front Door and
Tweeter)

B1025 02

B1025 04

B1025 01

-

Right Front Speaker Signal
Circuits (Front Door and
Tweeter)

B1035 02

B1035 04

B1035 01

-

Left Rear Speaker Signal
Circuits (Rear Door)

B1045 02

B1045 04

B1045 01

-

Right Rear Speaker Signal
Circuits (Rear Door)

B1055 02

B1055 04

B1055 01

-

Front Center Speaker Signal
Circuits (Center IP)

B1065 02

B1065 04

B1065 01

-

Subwoofer Low Level Audio
Signal Circuits (Center
Console)

B1075 02

B1075 04

B1075 01

-

Left Midrange Speaker Signal
Circuits (LR D-Pillar)

B1085 02

B1085 04

B1085 01

-

Right Midrange Speaker
Signal Circuits (RR D-Pillar)

B1095 02

B1055 04

B1095 01

-

2008 Chevrolet Silverado 1500

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and type of music, as well as the volume setting of the system. Low volume and talk settings will
measure around 1V AC and less, where constant music may measure 3V AC and slightly higher.
In an amplified audio system, these similar AC voltage measurements may be slightly higher on
the output of the amplifier, and the typical AC voltage readings at the output of the radio are less
than 1V AC.

Diagnostic Aids

The front tweeter speakers are connected to the same channel as the front door speakers.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

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, Rear Seat Audio (RSA) OFF(if equipped), adjust the fade and balance controls on the
radio to test all four channels individually. Each of the four channels should produce clear and
even sound.

Circuit/System Testing

2008 Chevrolet Silverado 1500

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

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