GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2007 🢒 Grand Prix 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC B1025, B1035, B1045, or B1055

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.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B1025: Speaker Output Shorted to Ground or Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Left Front Speaker Output (+)/Left Front Low Level Audio Signal (+)

B1025*

1

B1025*

--

Left Front Speaker Output (-)/Left Front Low Level Audio Signal (-)

B1025*

1

B1025*

--

Right Front Speaker Output (+)/Right Front Low Level Audio Signal (+)

B1025*

1

B1025*

--

Right Front Speaker Output (-)/Right Front Low Level Audio Signal (-)

B1025*

1

B1025*

--

Left Rear Speaker Output (+)/Left Rear Low Level Audio Signal (+)

B1025*

1

B1025*

--

Left Rear Speaker Output (-)/Left Rear Low Level Audio Signal (-)

B1025*

1

B1025*

--

Right Rear Speaker Output (+)/Right Rear Low Level Audio Signal (+)

B1025*

1

B1025*

--

Right Rear Speaker Output (-)/Right Rear Low Level Audio Signal (-)

B1025*

1

B1025*

--

1. No or reduced sound from speaker

* Noticeable Distorted Audio Possible

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. 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

The radio is ON.

Conditions for Setting the DTC

A short to voltage or a short to ground is detected on a speaker output signal circuit.

Action Taken When the DTC Sets

The radio disables its outputs on one or more channels, producing no sound.

Conditions for Clearing the DTC
    •  A current DTC will clear when the conditions for setting are no longer seen.
    • A history DTC will clear after 100 malfunction free ignition cycles.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

Entertainment/Communication Connector End Views

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

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

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification

Radio ON, adjust the fade and balance controls on the radio to test all four channels individually. All speakers should function properly. If a DTC is set, the corresponding speaker may produce no sound.

Circuit/System Testing

Without Amplifier

  1. Ignition OFF, disconnect the harness connector at the appropriate speaker.
  2. Radio ON, test for 5.0-7.5 volts between the signal circuit terminal A and ground.
    3. ⇒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. Test for 5.0-7.5 volts between the signal circuit terminal B and ground.
    4. ⇒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.
  4. If all circuits test normal, test or replace the speaker.

With Amplifier

  1. Ignition OFF, disconnect the C3 connector at the amplifier.
  2. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminal listed below and ground.
    3. • Left front low audio signal (+) - terminal 1
    • Left front low audio signal (-) - terminal 2
    • Right front low audio signal (+) - terminal 10
    • Right front low audio signal (-) - terminal 9
    • Left rear low audio signal (+) - terminal 4
    • Left rear low audio signal (-) - terminal 3
    • Right rear low audio signal (+) - terminal 11
    • Right rear low audio signal (-) - terminal 12
    ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
    ⇒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.
  3. If all circuits test normal, replace the amplifier.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Speaker Replacement Reference
    •  Control Module References for radio or amplifier replacement, setup, and programming