Buick Regal: DTC B1025-B1135 (UQ3 without NKC)

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 for an overview of each diagnostic category.

DTC Descriptors

DTC B1025

Left Front Audio Output Circuit

DTC B1035

Right Front Audio Output Circuit

DTC B1045

Left Rear Audio Output Circuit

DTC B1055

Right Rear Audio Output Circuit

For symptom byte information refer to Symptom Byte List.

Diagnostic Fault Information

1. No or reduced audio from speaker (s) on the affected audio circuit.
2. Noticeable audio distortion may be present.

Circuit/System Description

Each of the audio output channel circuits (+) and (-), at the radio have a DC bias voltage that is approximately one half of battery voltage. When using a DMM, each of the audio output channel circuits will measure approximately 6.5 V 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. The frequency (Hz) of the AC voltage signal is directly related to the frequency of the input (audio source playing) to the audio system. Both the DC bias voltage and the AC voltage signals are needed for the audio system to properly produce sound.

Conditions for Running the DTC

• Vehicle in Service Mode/Ignition is ON or in the ACC position
• The system voltage is 9-16 V
• The test is run once during radio wake up

Conditions for Setting the DTC

B1025 01, B1035 01, B1045 01, B1055 01

The radio detects a short to voltage on the specified audio (+) or (-) circuit.

B1025 02, B1035 02, B1045 02, B1055 02

The radio detects a short to ground on the specified audio (+) or (-) circuit.

B1025 04, B1035 04, B1045 04, B1055 04

The radio detects an open on the specified audio (+) or (-) circuit.

Action Taken When the DTC Sets

The radio continues to send the output signal to the speaker signal circuit with the current fault.

Conditions for Clearing the DTC

• A current DTC clears when the conditions for setting the DTC are no longer present and the ignition has been cycled from OFF to ON.
• A history DTC clears after 50 malfunction-free ignition cycles.

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.
• The test tones on the CD may be copied to a USB drive or other device to use during testing.
• If the speaker or surrounding interior trim is found to be loose or improperly secured, correctly secure the item.
• If equipped with an Active Noise Cancellation system that utilizes an ANC module, the module acts as a pass-through for the high level audio signals from the radio to the speakers.

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

Description and Operation

Radio/Audio System Description and Operation (IO6) , Radio/Audio System Description and Operation (IOB) , or Radio/Audio System Description and Operation (IOS/IOT/IOU).

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/vehicle in Service Mode, A11 Radio 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

NOTE: Some circuits supply audio signals to more than one speaker. It may be necessary to disconnect all speakers on the affected audio circuit when performing circuit tests.

1. Ignition OFF/vehicle OFF, disconnect the harness connector at the appropriate P19 Speaker.

Ignition ON, A11 Radio ON, mute OFF.

2. Test for 5 - 7 V between each audio signal circuit terminal 1 and terminal 2 and ground.

• If less than 5 V

1. Ignition OFF/vehicle OFF, disconnect the appropriate speaker harness connector at the A11 Radio.
2. Test for infinite resistance between the signal circuits 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 A11 Radio.

• If greater than 7 V

1. Ignition OFF/vehicle OFF, disconnect the appropriate speaker harness connector at the A11 Radio. Ignition ON/vehicle in Service Mode.
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 A11 Radio.

• Go to next step: If between 5 - 7 V

3. Test or replace the P19 Speaker.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Speaker Replacement Reference
• Refer to Control Module References for radio replacement, programming, and setup.

READ NEXT: