Reduced Volume - One or More Speakers

Reduced Volume - One or More Speakers

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



Circuit/System Description

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. Therefore each of the audio output channel circuits will measure approximately 6.5V DC when using a DMM. The audio music or talking being played on the audio system is produced by a a varying AC voltage that is centered around the DC bias voltage on the same circuit. The AC voltage measured on these circuits on the output of a radio that is not amplified will be approximately 1-3V AC when using a DMM. The AC voltage is what causes the speaker cone to move and produce the sound. This voltage will vary depending on what type of audio is being listened to, talk or music, and type of music, and the volume setting of the system. Low volume and talk settings will measure around 1 V AC and less, where constant music may measure 3 V 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 .


Reference Information
Schematic Reference

Radio/Navigation System Schematics (Radio/Navigation System Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Radio/Audio System Description and Operation (Radio/Audio System Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for Scan Tool information.


Circuit/System Verification

Adjust the fade and balance controls on the radio to test all four channels individually. All speakers should function properly.


Speaker(s) - Reduced Volume

Important: The following information lists the most probable cause of the concern to the least probable cause. If the list leads to the replacement of a component, always inspect for a poor connection before proceeding with replacement. Refer to Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics) and Connector Repairs (Component Tests and General Diagnostics) .




Without RPO U87
1. Speaker output circuit high resistance-Test the appropriate speaker output circuits for high resistance.
2. Defective speaker-Replace the appropriate speaker. Refer to Speaker Replacement Reference (Speaker Replacement Reference) .



With RPO U87
1. Speaker output circuit high resistance-Test the appropriate speaker output circuits for high resistance.
2. Low level audio circuit open-Test the appropriate low level audio circuit for an open. .
3. Defective speaker-Replace the appropriate speaker. Refer to Speaker Replacement Reference (Speaker Replacement Reference) .



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Speaker Replacement Reference (Speaker Replacement Reference)
* Control Module References (Programming and Relearning)for radio or amplifier replacement, setup, and programming