B1055

DTC B1025, B1035, B1045, or B1055

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.

DTC Descriptor
DTC B1025
- Audio Output Circuit Shorted to Battery or Ground

Diagnostic Fault Information





Circuit/System Description

Each of the audio output channel circuits (+) and (-), at the radio and audio amplifier 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, 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.

Conditions for Running the DTC

* Radio ON.
* Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

The DTC will set when the radio detects a short to voltage or short to ground in any of the low level audio signal circuits (+) and (-).

Action Taken When the DTC Sets

No sound is present from one or more of the speakers.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information
Schematic Reference

Radio/Navigation System Schematics (Radio/Navigation System Schematics)
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 Testing RPO U66

1. Ignition OFF, disconnect the X2 harness connector at the audio amplifier.
2. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminal listed below and ground.

* Left front low level audio signal (+) terminal A7
* Left front low level audio signal (-) terminal A6
* Right front low level audio signal (+) terminal B6
* Right front low level audio signal (-) terminal B7
* Left rear low level audio signal (+) terminal A4
* Left rear low level audio signal (-) terminal A5
* Right rear low level audio signal (+) terminal B5
* Right rear low level audio signal (-) terminal B4

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

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

Circuit/System Testing RPO U65

1. Ignition OFF, disconnect the X2 harness connector at the audio amplifier.
2. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminal listed below and ground.

* Left front low level audio signal (+) terminal B10
* Left front low level audio signal (-) terminal B9
* Right front low level audio signal (+) terminal B8
* Right front low level audio signal (-) terminal B7
* Left rear low level audio signal (+) terminal B6
* Left rear low level audio signal (-) terminal B5
* Right rear low level audio signal (+) terminal B4
* Right rear low level audio signal (-) terminal B3

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

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

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 audio amplifier and radio replacement, setup, and programming