Buick Regal: DTC B1025-B1135 (UQ3 with 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

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

• 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 replicates the high level audio signals from the radio to the speakers. If the module malfunctions, all the speakers may become inop.

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, 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 but not all.

Refer to Circuit/System Testing One Speaker.

• If audio is Inoperative from all speakers.

Refer to Circuit/System Testing All Speakers.

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

3. All OK.

Circuit/System Testing

One Speaker

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, 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, disconnect the appropriate harness connector at the K108 Active Noise Cancellation Module / T3 Audio Amplifier.
2. Test for infinite resistance between the appropriate 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 K108 Active Noise Cancellation Module / T3 Audio Amplifier.

• If greater than 7 V

1. Ignition OFF, disconnect the appropriate harness connector at the K108 Active Noise Cancellation Module / T3 Audio Amplifier.
2. Ignition ON, A11 Radio ON, mute OFF. Test for less than 1 V between the appropriate signal circuit and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, replace the K108 Active Noise Cancellation Module / T3 Audio Amplifier.

• Go to next step: If between 5 - 7 V

3. Ignition OFF, disconnect the appropriate harness connector at the K108 Active Noise Cancellation Module / T3 Audio Amplifier.

4. Ignition ON, A11 Radio ON, mute OFF. Test for 5 - 7 V between each appropriate audio signal circuit from the A11 Radio and Ground.

• If less than 5 V

1. Ignition 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, disconnect the appropriate speaker harness connector at the A11 Radio.

   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 A11 Radio.

• Go to next step: If between 5 - 7 V

5. Test or replace the P19 Speaker.

All Speakers

1. Ignition OFF, disconnect the X1 harness connector at the K108 Active Noise Cancellation Module / T3 Audio Amplifier.

2. Test for less than 10 Ω between the ground circuit terminal 8 and ground.

• If 10 Ω or greater

1. Test for less than 2 Ω in the ground circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, repair the open/high resistance in the ground connection.

• Go to next step: If less than 10 Ω

3. Verify that a test lamp illuminates between the B+ circuit terminal 4 and ground.

• If the test lamp does not illuminate

1. Remove the test lamp.
2. Test for less than 2 Ω in the B+ circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.

• Go to next step: If the test lamp illuminates

4. Ignition ON, A11 Radio ON.

5. Verify that a test lamp illuminates between the control circuit terminal 3 and ground.

• If the test lamp does not illuminate

1. Ignition OFF, disconnect the X1 harness connector at the A11 Radio.
2. Test for infinite resistance between the control 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 control 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.

• Go to next step: If the test lamp illuminates

6. Test for 5 - 7 V between any audio signal circuit from the A11 Radio and Ground.

• If not between 5 - 7 V

Test or replace the A11 Radio.

• Go to next step: If between 5 - 7 V

7. Test or replace the K108 Active Noise Cancellation Module / T3 Audio Amplifier.

Repair Instructions

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

READ NEXT: