GM Service Manual Online
For 1990-2009 cars only

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.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Left Front Speaker Signal (+)

B1025*

B1025*

B1025*

--

Left Front Speaker Signal (-)

B1025*

B1025*

B1025*

--

Right Front Speaker Signal (+)

B1035*

B1035*

B1035*

--

Right Front Speaker Signal (-)

B1035*

B1035*

B1035*

--

Left Rear Speaker Signal (+)

B1045*

B1045*

B1045*

--

Left Rear Speaker Signal (-)

B1045*

B1045*

B1045*

--

Right Rear Speaker Signal (+)

B1055*

B1055*

B1055*

--

Right Rear Speaker Signal (-)

B1055*

B1055*

B1055*

--

* Noticeable audio distortion possible.

Circuit/System Description

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

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

Conditions for Running the DTC

The radio is ON.

Conditions for Setting the DTC

The following conditions are present for 250 ms or longer:

    • One of the speaker signal circuits is shorted to battery.
    • One of the speaker signal circuits is shorted to ground.
    • One of the speaker signal circuits is open.

Action Taken When the DTC Sets

The radio disables the audio signal to the speaker with the current fault, producing no sound from the speaker.

Conditions for Clearing the DTC

    • The conditions for setting the DTC are no longer present.
    • A history DTC clears after 100 malfunction-free ignition cycles.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

Component 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

Control Module References for scan tool information

Circuit/System Verification

Radio ON, adjust the fade and balance controls on the radio to test all channels individually. Each channel should produce clear and even sound.

Circuit/System Testing

  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.
  4. Test for 5.0-7.5 volts between the signal circuit terminal B and ground.
  5. 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.
  6. If all circuits test normal, replace the speaker.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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