GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Generic 🢒 2005 🢒 Unit Repair 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 DTC B1025, B1035, B1045, or B1055

Circuit Description

The radio head unit provides four discrete channels to the speakers. Each channel consists of two wires that connect to a speaker. During normal operation, the radio applies approximately 5-6 volts to the plus (+) and minus (-) terminals at the speaker. The terminals attach to the speaker voice coil.

In order for the speaker to produce sound, the amplifier in the radio will raise the voltage on one terminal and lower the voltage on the opposite terminal, then quickly reverse the polarity. The constant switching of the electrical signal causes the voice coil and speaker cone to move rapidly in two directions. The movement of the speaker cone produces sound.

DTC Descriptors

This diagnostic procedure supports the following DTC:

    • DTC B1025 LF Audio Output Circuit
    • DTC B1035 RF Audio Output Circuit
    • DTC B1045 LR Audio Output Circuit
    • DTC B1055 RR Audio Output Circuit

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC Symptom

DTC Symptom Descriptor

01

Short to Battery

02

Short to Ground

Conditions for Running the DTC

B1025-B1055 01 and 02

The following are conditions that must be present in order for the radio to enable the diagnostics.

    • The radio is in the ACCESSORY, RUN, or RAP power mode.
    • The system voltage is at least 9.0 volts and no more than 16.0 volts.

Conditions for Setting the DTC

The following conditions are present for 250 ms or longer.

B1025-B1055 01

One of the speaker output circuits is shorted to battery.

B1025-B1055 02

One of the speaker output circuits is shorted to ground.

Action Taken When the DTC Sets

The radio disables the audio output 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.
    • The radio receives the clear code command from the scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step verifies that the DTC is still present.

    2.

  2. This step isolates the fault condition.

Step

Action

Yes

No

Schematic Reference: Radio/Audio System Schematics

Connector End View Reference: Entertainment Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, monitor the DTC Information for DTC B1025, B1035, B1045, or B1055.

Does the scan tool indicate that DTC B1025, B1035, B1045, or B1055 is current?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3

Test the affected speaker output channel from the radio for a short to ground or voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 4

4

Inspect for poor connections at the harness connector of the radio. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 5

5
  1. Replace the radio. Refer to Radio Replacement .
  2. Perform the VIN Relearn procedure with a scan tool. On the scan tool, go to Module Replacement/Setup in Vehicle Control Systems and select Radio.

Did you complete the replacement?

Go to Step 6

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6

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2