Buick Regal: DTC B1025-B1135 (UQA with IO5/IO6)

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.
• Refer to Diagnostic Procedure Instructions provide an overview of each diagnostic category.

DTC Descriptors

DTC B1025

Audio Output 1 Circuit

DTC B1035

Audio Output 2 Circuit

DTC B1045

Audio Output 3 Circuit

DTC B1055

Audio Output 4 Circuit

DTC B1065

Audio Output 5 Circuit

DTC B1075

Audio Output 6 Circuit

DTC B1085

Audio Output 7 Circuit

For symptom byte information refer to Symptom Byte List.

Diagnostic Fault Information

Circuit/System Description

The Media Oriented Systems Transport (MOST) is a high-speed multimedia network technology. The serial MOST bus uses a ring topology and synchronous data communication to transmit audio, video, data and control information between any devices attached.

The audio amplifier is a participant on the MOST network. The audio amplifier receives audio inputs and control information from the MOST bus.

Each of the audio output channel circuits (+) and (-), at the audio amplifier have a DC bias voltage that is approximately 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.

Diagnostic Aids

• Improper speaker mounting or loose trim may cause an audible buzz or distortion. Inspect the appropriate speaker and the surrounding interior trim for proper and secure mounting.

  The EL-50334-6 Audio System Diagnostic CD contains audio tracks that can be used to duplicate and isolate such concerns. Tracks 11 and 12 contain audio sweep tones for testing for speaker and grill rattles.

  If the speaker or surrounding interior trim is found to be loose or improperly secured, correctly secure the item.

• The test tones on the CD may be copied to a USB drive or other device to use during testing.
• Some audio output circuits are connected to more than one speaker, dependent on vehicle equipment. It may be necessary to disconnect one or more speakers during testing of some circuits.

Conditions for Running the DTC

NOTE: DTC B1325 must not be set as current for the amplifier to run any of the following tests.

DTC B1025 01, B1035 01, B1045 01, B1055 01, B1065 01, B1075 01, B1085 01

The test is run initially upon amplifier wake-up, and periodically every one second after amplifier operation begins.

DTC B1025 02, B1035 02, B1045 02, B1055 02, B1065 02, B1075 02, B1085 02

The test is run initially upon amplifier wake-up, and periodically every one second after amplifier operation begins.

DTC B1025 04, B1035 04, B1045 04, B1055 04, B1065 04, B1075 04, B1085 04

The test is run once during amplifier wake-up.

Conditions for Setting the DTC

DTC B1025 01, B1035 01, B1045 01, B1055 01, B1065 01, B1075 01, B1085 01

A short to voltage is detected on the specified (+) or (-) signal circuit

DTC B1025 02, B1035 02, B1045 02, B1055 02, B1065 02, B1075 02, B1085 02

A short to ground is detected on the specified (+) or (-) signal circuit

DTC B1025 04, B1035 04, B1045 04, B1055 04, B1065 04, B1075 04, B1085 04

An open is detected on the specified (+) or (-) signal circuit

Action Taken When the DTC Sets

The amplifier mutes the output channel and no sound is present from the speaker (s) that have a current circuit fault.

Conditions for Clearing the DTC

• The condition for setting the DTC is no longer present.
• A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Radio/Navigation System Wiring Schematics (IOB) , Radio/Navigation System Wiring Schematics (IOR) or Radio/Navigation System Wiring Schematics (IO5/IO6) , or Radio/Navigation System Wiring Schematics (IOS/IOT).

Connector End View Reference

Component Connector End View Index

Electrical Information Reference

• Refer to Circuit Testing
• Refer to Connector Repairs
• Refer to Testing for Intermittent Conditions and Poor Connections
• Refer to Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information.

Circuit/System Verification

1. Ignition ON, infotainment system ON, mute OFF.

2. Verify clear audio is heard from each speaker, adjusting fade and balance controls to test each speaker individually.

• If audio is inoperative from one or more speakers, or the audio emitted is not clear

Refer to Circuit/System Testing.

• Go to next step: If clear audio is heard from all speakers

3. All OK.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate P19 Speaker. Ignition ON, infotainment system ON, mute OFF.

2. Test for 5 - 7 V between the appropriate signal circuit terminals listed below and ground.

• Door and Center I/P speakers audio (-) circuit terminal 1
• Door and Center I/P speakers audio (+) circuit terminal 2
• Left Subwoofer speakers audio (-) circuit terminal 1
• Left Subwoofer speakers audio (+) circuit terminal 2
• Right Subwoofer speakers audio (-) circuit terminal 3
• Right Subwoofer speakers audio (+) circuit terminal 4
• If less than 5 V

1. Ignition OFF, disconnect the X1 and X2 harness connectors at the T3 Audio Amplifier.
2. Test for infinite resistance between the signal circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the signal circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the T3 Audio Amplifier.

• If greater than 7 V

1. Ignition OFF, disconnect the X1 and X2 harness connectors at the T3 Audio Amplifier.

   Ignition ON.

2. Test for less than 1 V between the signal circuit and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, replace the T3 Audio Amplifier.

• Go to next step: If between 5 - 7 V

3. Test or replace the P19 Speaker.

Repair Instructions

• Refer to Speaker Replacement Reference
• Refer to Control Module References for audio amplifier replacement, programming, and setup.
• Perform the Diagnostic Repair Verification after completing the repair.

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