GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 SRX 🢒 DTC 🢒 DTC B1025-B1125

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 01: Audio Output 1 Circuit Short to Battery - Left Front

DTC B1025 02: Audio Output 1 Circuit Short to Ground - Left Front

DTC B1025 04: Audio Output 1 Circuit Open - Left Front

DTC B1035 01: Audio Output 2 Circuit Short to Battery -- Right Front

DTC B1035 02: Audio Output 2 Circuit Short to Ground --Right Front

DTC B1035 04: Audio Output 2 Circuit Open --Right Front

DTC B1045 01:  Audio Output 3 Circuit Short to Battery --Left Rear

DTC B1045 02:  Audio Output 3 Circuit Short to Ground -- Left Rear

DTC B1045 04:  Audio Output 3 Circuit Open -- Left Rear

DTC B1055 01:  Audio Output 4 Circuit Short to Battery -- Right Rear

DTC B1055 02:  Audio Output 4 Circuit Short to Ground -- Right Rear

DTC B1055 04:  Audio Output 4 Circuit Open -- Right Rear

DTC B1065 01:  Audio Output 5 Circuit Short to Battery -- Center IP

DTC B1065 02:  Audio Output 5 Circuit Short to Ground -- Center IP

DTC B1065 04:  Audio Output 5 Circuit Open -- Center IP

DTC B1075 01:  Audio Output 6 Circuit Short to Battery -- Subwoofer

DTC B1075 02:  Audio Output 6 Circuit Short to Ground -- Subwoofer

DTC B1075 04:  Audio Output 6 Circuit Open -- Subwoofer

DTC B1085 01:  Audio Output 7 Circuit Short to Battery -- LR D Pillar

DTC B1085 02:  Audio Output 7 Circuit Short to Ground -- LR D Pillar

DTC B1085 04:  Audio Output 7 Circuit Open -- LR D Pillar

DTC B1095 01:  Audio Output 8 Circuit Short to Battery -- RR D Pillar

DTC B1095 02:  Audio Output 8 Circuit Short to Ground -- RR D Pillar

DTC B1095 04:  Audio Output 8 Circuit Open -- RR D Pillar

DTC B1105 01:  Audio Output 9 Circuit Short to Battery -- LF IP

DTC B1105 02:  Audio Output 9 Circuit Short to Ground -- LF IP

DTC B1105 04:  Audio Output 9 Circuit Open -- LF IP

DTC B1115 01:  Audio Output 10 Circuit Short to Battery -- RF IP

DTC B1115 02:  Audio Output 10 Circuit Short to Ground -- RF IP

DTC B1115 04:  Audio Output 10 Circuit Open -- RF IP

DTC B1125 01:  Audio Output 11 Circuit Short to Battery -- Center Console

DTC B1125 02:  Audio Output 11 Circuit Short to Ground -- Center Console

DTC B1125 04:  Audio Output 11 Circuit Open -- Center Console

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Amplifier B+

1

1

--

--

Amplifier Control

B1287 02

B1287 04

B1287 01

--

Speaker Output Signal Circuit (+)

B1XXX 02*,**

B1XXX 04*,**

B1XXX 01*,**

--

Speaker Output Signal Circuit (-)

B1XXX 02*,**

B1XXX 04*,**

B1XXX 01*,**

--

Amplifier Ground

--

1

--

--

1. Amplifier inoperative/no sound from speaker

* Sets associated speaker DTC with appropriate syptom type -- see DTC descriptors

** Noticeable audio distortion 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. In an amplified audio system, these similar AC voltage measurements may be slightly higher then the radio outputs.

Conditions for Running the DTC
    • Radio ON.
    • Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

DTC Set By The Radio

The DTC will set when the radio detects a short to voltage, short to ground, or an open/high resistance in any of the low level audio signal circuits (+) and (-).

DTC Set By The Audio Amplifier

The DTC will set when the audio amplifier detects a short to voltage, short to ground, or an open/high resistance in any of the speaker output circuits (+) and (-).

Action Taken When the DTC Sets

No sound is present from one or more of the speakers.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists.
    • A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

The supporting DTCs can be set by either the radio or the audio amplifier. When a DTC is set by the radio, diagnose suspect audio signal circuits to the audio amplifier. For DTCs set by the audio amplifier, diagnose audio output circuits to the speakers from the amplifier.

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

Note: DTCs that set in the radio for Right Hand Drive (RHD) vehicles will correspond with the speakers on the opposite side of the vehicle such as a left speaker DTC will be for the right speaker. The amplifier will set DTCs correctly for both Left and Right Hand Drive.

DTC Set By The Radio LHD RPO UQA

  1. Ignition OFF, disconnect the X3 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 level audio signal (+) - terminal 15
    • Left front low level audio signal (-) - terminal 7
    • Right front low level audio signal (+) - terminal 14
    • Right front low level audio signal (-) - terminal 6
    • Left rear low level audio signal (+) - terminal 13
    • Left rear low level audio signal (-) - terminal 5
    • Right rear low level audio signal (+) - terminal 12
    • Right rear low level audio signal (-) - terminal 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.
  3. If all circuits test normal, replace the amplifier.

DTC Set By The Radio RHD RPO UQA

  1. Ignition OFF, disconnect the X3 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 level audio signal (+) - terminal 14
    • Left front low level audio signal (-) - terminal 6
    • Right front low level audio signal (+) - terminal 15
    • Right front low level audio signal (-) - terminal 7
    • Left rear low level audio signal (+) - terminal 12
    • Left rear low level audio signal (-) - terminal 4
    • Right rear low level audio signal (+) - terminal 13
    • Right rear low level audio signal (-) - terminal 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.
  3. If all circuits test normal, replace the amplifier.

DTC Set By The Radio RPO UQS

  1. Ignition OFF, disconnect the X3 and X4 harness connectors 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 level audio signal (+) - terminal 11 X3
    • Left front low level audio signal (-) - terminal 12 X3
    • Right front low level audio signal (+) - terminal 3 X3
    • Right front low level audio signal (-) - terminal 4 X3
    • Left rear low level audio signal (+) - terminal 11 X4
    • Left rear low level audio signal (-) - terminal 12 X4
    • Right rear low level audio signal (+) - terminal 3 X4
    • Right rear low level audio signal (-) - terminal 4 X4
    ⇒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. If all circuits test normal, replace the amplifier.

DTC Set By The Radio with RPO UQS & U42

  1. Ignition OFF, disconnect the X2 harness connector at the rear seat audio (RSA) module.
  2. Radio ON, RSA OFF, test for 5.0-7.5 volts between the appropriate signal circuit terminal listed below and ground.
    3. • Left rear low level audio signal (+) - terminal 1
    • Left rear low level audio signal (-) - terminal 2
    • Right rear low level audio signal (+) - terminal 3
    • Right rear low level audio signal (-) - terminal 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.
  3. Ignition OFF, reconnect the X2 harness at the RSA and disconnect the X3 and X4 harness connectors at the amplifier.
  4. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminal listed below and ground:
    5. • Left front low level audio signal (+) - terminal 11 X3
    • Left front low level audio signal (-) - terminal 12 X3
    • Right front low level audio signal (+) - terminal 3 X3
    • Right front low level audio signal (-) - terminal 4 X3
    ⇒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.
  5. Ignition ON, radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminals listed below and ground:
    6. • Left rear low level audio signal (+) - terminal 11 X4
    • Left rear low level audio signal (-) - terminal 12 X4
    • Right rear low level audio signal (+) - terminal 3 X4
    • Right rear low level audio signal (-) - terminal 4 X4
    ⇒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 RSA module.
    ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the RSA module.
  6. If all audio circuits test normal, replace the amplifier.

DTC Set By The Audio Amplifier LHD RPO UQA

  1. Ignition OFF, disconnect the X1 and X2 connectors at the amplifier.
  2. Radio ON, test for less than 1 volt between the appropriate signal circuit terminal listed below and ground:
    3. • Left front speaker output (+) - terminal 5 X1
    • Left front speaker output (-) - terminal 1 X1
    • Right front speaker output (+) - terminal 8 X2
    • Right front speaker output (-) - terminal 7 X2
    • Left rear speaker output (+) - terminal 15 X2
    • Left rear speaker output (-) - terminal 16 X2
    • Right rear speaker output (+) - terminal 2 X2
    • Right rear speaker output (-) - terminal 1 X2
    • Front center speaker output (+) - terminal 4 X2
    • Front center speaker output (-) - terminal 3 X2
    • Right subwoofer speaker output (+) - terminal 7 X1
    • Right subwoofer speaker output (-) - terminal 2 X1
    • Rear subwoofer speaker output (+) - terminal 6 X1
    • Rear subwoofer speaker output (-) - terminal 3 X1
    ⇒If greater than the specified range, test both circuits of the affected speaker for a short to voltage.
  3. Radio ON, test for greater than 1 ohm between the appropriate signal circuit terminal listed below and ground:
    4. • Left front speaker output (+) - terminal 5 X1
    • Left front speaker output (-) - terminal 1 X1
    • Right front speaker output (+) - terminal 8 X2
    • Right front speaker output (-) - terminal 7 X2
    • Left rear speaker output (+) - terminal 15 X2
    • Left rear speaker output (-) - terminal 16 X2
    • Right rear speaker output (+) - terminal 2 X2
    • Right rear speaker output (-) - terminal 1 X2
    • Front center speaker output (+) - terminal 4 X2
    • Front center speaker output (-) - terminal 3 X2
    • Right subwoofer speaker output (+) - terminal 7 X1
    • Right subwoofer speaker output (-) - terminal 2 X1
    • Rear subwoofer speaker output (+) - terminal 6 X1
    • Rear subwoofer speaker output (-) - terminal 3 X1
    ⇒If less than the specified range, test both circuits of the affected speaker for a short to ground.
  4. Ignition OFF, reconnect all harness connectors at the amplifier.
  5. Disconnect the appropriate speaker.
  6. Radio ON, test for 5.0-7.5 volts between the signal circuit terminals and ground.
    7. ⇒If less then the specified range, test the circuit for an open/high resistance. If the circuit tests normal, replace the amplifier.
    ⇒If greater then the specified range, test the circuit for a short to voltage. If the circuit tests normal, replace the amplifier.
  7. If the circuits tests normal, replace the appropriate speaker.

DTC Set By The Audio Amplifier RHD RPO UQA

  1. Ignition OFF, disconnect the X1 and X2 connectors at the amplifier.
  2. Radio ON, test for less than 1 volt between the appropriate signal circuit terminal listed below and ground:
    3. • Left front speaker output (+) - terminal 8 X2
    • Left front speaker output (-) - terminal 7 X2
    • Right front speaker output (+) - terminal 5 X1
    • Right front speaker output (-) - terminal 1 X1
    • Left rear speaker output (+) - terminal 2 X2
    • Left rear speaker output (-) - terminal 1 X2
    • Right rear speaker output (+) - terminal 16 X2
    • Right rear speaker output (-) - terminal 15 X2
    • Front center speaker output (+) - terminal 4 X2
    • Front center speaker output (-) - terminal 3 X2
    • Right subwoofer speaker output (+) - terminal 7 X1
    • Right subwoofer speaker output (-) - terminal 2 X1
    • Rear subwoofer speaker output (+) - terminal 6 X1
    • Rear subwoofer speaker output (-) - terminal 3 X1
    ⇒If greater than the specified range, test both circuits of the affected speaker for a short to voltage.
  3. Radio ON, test for infinite resistance between the appropriate signal circuit terminal listed below and ground:
    4. • Left front speaker output (+) - terminal 8 X2
    • Left front speaker output (-) - terminal 7 X2
    • Right front speaker output (+) - terminal 5 X1
    • Right front speaker output (-) - terminal 1 X1
    • Left rear speaker output (+) - terminal 2 X2
    • Left rear speaker output (-) - terminal 1 X2
    • Right rear speaker output (+) - terminal 16 X2
    • Right rear speaker output (-) - terminal 15 X2
    • Front center speaker output (+) - terminal 4 X2
    • Front center speaker output (-) - terminal 3 X2
    • Right subwoofer speaker output (+) - terminal 7 X1
    • Right subwoofer speaker output (-) - terminal 2 X1
    • Rear subwoofer speaker output (+) - terminal 6 X1
    • Rear subwoofer speaker output (-) - terminal 3 X1
    ⇒If less than the specified value, test both circuits of the affected speaker for a short to ground.
  4. Igntion OFF, reconnect all harness connectors at the amplifier.
  5. Disconnect the appropriate speaker.
  6. Radio ON, test for 5.0-7.5 volts between the signal circuit terminals and ground.
    7. ⇒If less then the specified range test the circuit for an open/high resistance. If the circuit tests normal, replace the amplifier.
    ⇒If greater then the specified range, test the circuit for a short to voltage. If the circuit tests normal, replace the amplifier.
  7. If the circuit tests normal, replace the appropriate speaker.

DTC Set By The Audio Amplifier RPO UQS

  1. Ignition OFF, disconnect the X1 and X2 connectors at the amplifier.
  2. Radio ON, test for less than 1 volt between the appropriate signal circuit terminal listed below and ground:
    3. • Left front speaker output (+) - terminal 4 X2
    • Left front speaker output (-) - terminal 5 X2
    • Right front speaker output (+) - terminal 7 X2
    • Right front speaker output (-) - terminal 6 X2
    • Left rear speaker output (+) - terminal 16 X2
    • Left rear speaker output (-) - terminal 8 X2
    • Right rear speaker output (+) - terminal 15 X2
    • Right rear speaker output (-) - terminal 14 X2
    • Front center speaker output (+) - terminal 13 X2
    • Front center speaker output (-) - terminal 12 X2
    • Rear center console speaker output (+) - terminal 5 X1
    • Rear center console speaker output (-) - terminal 6 X1
    • Right subwoofer speaker output (+) - terminal 7 X1
    • Right subwoofer speaker output (-) - terminal 3 X1
    • Rear subwoofer speaker output (+) - terminal 1 X1
    • Rear subwoofer speaker output (-) - terminal 2 X1
    • Right rear D pillar speaker output (+) - terminal 3 X2
    • Right rear D pillar speaker output (-) - terminal 2 X2
    • Left rear D pillar speaker output (+) - terminal 11 X2
    • Left rear D pillar speaker output (-) - terminal 10 X2
    ⇒If greater than the specified range, test both circuits of the affected speaker for a short to voltage.
  3. Radio ON, test for infinite resistance between the appropriate signal circuit terminal listed below and ground:
    4. • Left front speaker output (+) - terminal 4 X2
    • Left front speaker output (-) - terminal 5 X2
    • Right front speaker output (+) - terminal 7 X2
    • Right front speaker output (-) - terminal 6 X2
    • Left rear speaker output (+) - terminal 16 X2
    • Left rear speaker output (-) - terminal 8 X2
    • Right rear speaker output (+) - terminal 15 X2
    • Right rear speaker output (-) - terminal 14 X2
    • Front center speaker output (+) - terminal 13 X2
    • Front center speaker output (-) - terminal 12 X2
    • Rear center console speaker output (+) - terminal 5 X1
    • Rear center console speaker output (-) - terminal 6 X1
    • Right subwoofer speaker output (+) - terminal 7 X1
    • Right subwoofer speaker output (-) - terminal 3 X1
    • Rear subwoofer speaker output (+) - terminal 1 X1
    • Rear subwoofer speaker output (-) - terminal 2 X1
    • Right rear D pillar speaker output (+) - terminal 3 X2
    • Right rear D pillar speaker output (-) - terminal 2 X2
    • Left rear D pillar speaker output (+) - terminal 11 X2
    • Left rear D pillar speaker output (-) - terminal 10 X2
    ⇒If less than the specified value, test both circuits of the affected speaker for a short to ground.
  4. Ignition OFF, reconnect all harness connectors at the amplifier.
  5. Disconnect the appropriate speaker.
  6. Radio ON, test for 5.0-7.5 volts between the signal circuit terminals and ground.
    7. ⇒If less then the specified range test the circuit for an open/high resistance. If the circuit tests normal, replace the amplifier.
    ⇒If greater then the specified range, test the circuit for a short to voltage. If the circuit tests normal, replace the amplifier.
  7. If the circuit tests normal, replace the appropriate speaker.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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