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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 CTS 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Speaker Malfunction

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

Amplifier B+

--

2

--

--

Speaker Output Circuit (+)

B1XXX 02*,**

B1XXX 04*,**

B1XXX 01*,**

--

Speaker Output Circuit (-)

B1XXX 02*,**

B1XXX 04*,**

B1XXX 01*,**

--

Subwoofer Signal (+)

B1075 02,**

1

B1075 01,**

--

Subwoofer Signal (-)

B1075 02,**

1

B1075 01,**

--

Amplifier Control

B1287 02

B1287 04

B1287 01

--

Amplifier Ground

--

2

--

--

1. No or reduced sound from subwoofer

2. Amplifier inoperative/no sound from speaker

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

** Noticeable audio distortion possible

Circuit/System Description

Each of the audio output channel circuits (+) and (-) have a varying AC mV signal that is produced by the radio and sent to the amplifier. The amplifier then processes these signals and passes the audio along with a DC bias voltage to the appropriate speakers. The audio being played on the system is produced by the varying AC voltage. 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. When using a DMM, each of the audio amplifier output channel circuits will measure approximately 6.5V DC.

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.
    • When equipped with an amplifier, it is possible for some individual circuit faults to affect more than one speakers operation. Perform diagnostic tests in the sequence listed to avoid misdiagnosis.

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, verify clear audio is heard from each audio speaker.

⇒If audio is inoperative from all speakers, refer to Amplifier Circuit Malfunction.
⇒If audio is inoperative from one or more, but not all, speakers or the audio emitted from the speakers is not clear, refer to the appropriate Speaker Circuit Malfunction.

Circuit/System Testing

Amplifier Circuit Malfunction

  1. Ignition OFF, disconnect the X1 harness connector at the audio amplifier.
  2. Ignition OFF, test for less than 1 volt between the ground circuit terminal 8 and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an short to voltage.
  3. Ignition OFF, test for less than 10 ohms between the ground circuit terminal 8 and ground.
    4. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, test for B+ between the B+ circuit terminal 4 and ground.
    5. ⇒If less then specified value, test the circuit for a short to ground, or an open/high resistance.
  5. Ignition OFF, disconnect the X3 harness connector at the audio amplifier.
  6. For RPO UQA only: Radio ON, test for B+ between the Entertainment remote enable circuit terminal 8 and ground.
    7. ⇒If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  7. If all circuits test normal, replace the audio amplifier.

Speaker Malfunction Radio Output Testing RPO UQA

  1. Ignition OFF, disconnect the X3 connector at the amplifier.
  2. Radio ON, test for a varying mV AC voltage reading between the appropriate signal circuit terminals listed below and ground.
    3. • Left front low level audio signal (+) - terminal 15 X3
    • Left front low level audio signal (-) - terminal 7 X3
    • Right front low level audio signal (+) - terminal 14 X3
    • Right front low level audio signal (-) - terminal 6 X3
    • Left rear low level audio signal (+) - terminal 13 X3
    • Left rear low level audio signal (-) - terminal 5 X3
    • Right rear low level audio signal (+) - terminal 12 X3
    • Right rear low level audio signal (-) - terminal 4 X3
    ⇒If the varrying Mv A/C voltage reading is not present, test the signal circuit for a short to voltage, 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.

Speaker Malfunction Radio Output Testing RPO UQS

  1. Ignition OFF, disconnect the X3 and X4 harness connectors at the amplifier.
  2. Ignition ON, radio ON, test for a varying mV AC voltage reading between the appropriate signal circuit terminals 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
    • Center channel low level audio signal (+) - terminal 13 X4
    • Center channel low level audio signal (-) - terminal 14 X4
    • Subwoofer low level audio signal (+) - terminal 5 X4
    • Subwoofer low level audio signal (-) - terminal 6 X4
    ⇒If the varrying Mv A/C voltage reading is not present, test the signal circuit for a short to voltage, 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.

Speaker Malfunction Amplifier Output Testing 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
    • Rear subwoofer speaker output (+) - terminal 7 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 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
    • Rear subwoofer speaker output (+) - terminal 7 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. If all circuits test normal, reconnect all harness connectors at the amplifier.
  5. Ignition ON, radio ON, disconnect the appropriate speaker.
  6. 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.

Speaker Malfunction Amplifier Output Testing RPO Code 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 tweeter speaker output (+) - terminal 4 X2
    • Left front tweeter speaker output (-) - terminal 5 X2
    • Right front tweeter speaker output (+) - terminal 7 X2
    • Right front tweeter 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
    • Left rear subwoofer speaker output (+) - terminal 5 X1
    • Left rear subwoofer speaker output (-) - terminal 6 X1
    • Right front speaker output (+) - terminal 7 X1
    • Right front speaker output (-) - terminal 3 X1
    • Left front speaker output (+) - terminal 1 X1
    • Left front speaker output (-) - terminal 2 X1
    • Right front speaker output (+) - terminal 7 X1
    • Right front speaker output (-) - terminal 3 X1
    • Left rear midrange speaker output (+) - terminal 11 X2
    • Left rear midrange 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 tweeter speaker output (+) - terminal 4 X2
    • Left front tweeter speaker output (-) - terminal 5 X2
    • Right front tweeter speaker output (+) - terminal 7 X2
    • Right front tweeter 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
    • Left rear subwoofer speaker output (+) - terminal 5 X1
    • Left rear subwoofer speaker output (-) - terminal 6 X1
    • Right front speaker output (+) - terminal 7 X1
    • Right front speaker output (-) - terminal 3 X1
    • Left front speaker output (+) - terminal 1 X1
    • Left front speaker output (-) - terminal 2 X1
    • Right front speaker output (+) - terminal 7 X1
    • Right front speaker output (-) - terminal 3 X1
    • Left rear midrange speaker output (+) - terminal 11 X2
    • Left rear midrange speaker output (-) - terminal 10 X2
    ⇒If less than the specified value, test both circuits of the affected speaker for a short to ground.
  4. If all circuits test normal, reconnect all harness connectors at the amplifier.
  5. Ignition OFF, 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.

Powered Subwoofer Malfunction RPO UQS

  1. Disconnect the harness connector at the inoperative subwoofer.
  2. Ignition ON, test for less than 1 volt between the ground circuit terminal B and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an short to voltage.
  3. Ignition OFF, test for less than 10 ohms between the ground circuit terminal B and ground
    4. ⇒If greater than specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, test for B+ between circuit terminal A and ground.
    5. ⇒If less then the specified value, test the B+ circuit for a short to ground or an open/high resistance.
  5. Radio ON, test for B+ between the radio audio mute signal circuit terminal C and ground.
    6. ⇒If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the amplifier.
  6. Radio ON, test for 5.0-7.5 volts between the signal circuit terminal E and ground.
    7. ⇒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 audio amplifier.
    ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the audio amplifier.
  7. Test for 5.0-7.5 volts between the signal circuit terminal D and ground.
    8. ⇒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 audio amplifier.
    ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the audio amplifier.
  8. If all circuits test normal, replace the subwoofer.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Speaker Replacement Reference
    •  Control Module References for amplifier or radio replacement