GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 STS 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 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+

--

1

--

--

Powerd Woofer B+

--

3

--

--

Amplifier Control

B1287 02

B1287 04

B1287 01

--

Amplifier Powerd Woofer Control

3

3

3

--

Low Level Audio Signal (+)

2

2

2

--

Low Level Audio Signal (-)

2

2

2

--

Speaker Output Signal (+)

2

2

2

--

Speaker Output Signal (-)

2

2

2

--

Powerd Woofer Ground

--

3

--

--

Amplifier Ground

--

1

--

--

1. No sound from speaker

2. Noticeable audio distortion possible

3. No or distorted audio from powered subwoofer/woofer

Circuit/System Description

Each of the audio output channel circuits (+) and (-), at the radio and audio amplifier 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.
    • 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 Speaker Circuit Malfunction.

Circuit/System Testing

Amplifier Circuit Malfunction

  1. Ignition OFF, disconnect the X2 harness connector at the audio amplifier.
  2. Ignition OFF, test for less than 10 Ω between the ground circuit terminal 2 and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, test for B+ on the B+ circuit terminal 1 and ground.
    4. ⇒If less than the specified value, test the B+ circuit for a short to ground or an open/high resistance.
  4. Radio ON, test for 0.6-1.0V between the amplifier control circuit terminal 11 and ground.
    5. ⇒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.
    ⇒If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the radio.
  5. If all circuits test normal, replace the audio amplifier.

Speaker Circuit Malfunction YQ2

  1. Disconnect the X1 harness connector at the audio amplifier.
  2. Radio ON, test for 5.0-7.5V between the appropriate audio signal circuit terminal listed below and ground.
    3. • Left front low level (+) - terminal 1
    • Left front low level (-) - terminal 17
    • Right front low level (+) - terminal 2
    • Right front low level (-) - terminal 18
    • Left rear low level (+) - terminal 5
    • Left rear low level (-) - terminal 21
    • Right rear low level (+) - terminal 6
    • Right rear low level (-) - terminal 22
    • Center channel low level (+) - terminal 3
    • Center channel and subwoofer low level audio common (-) - terminal 19
    • Sub woofer low level (+) - 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, connect the X1 harness connector at the audio amplifier.
  4. Disconnect the X2 harness connector at the audio amplifier.
  5. Ignition ON, test for less than 1V between the appropriate speaker signal circuit terminal listed below and ground.
    6. • Front center speaker output (+) - terminal 9
    • Front center speaker output (-) - terminal 21
    • Left front woofer speaker output (+) - terminal 13
    • Left front woofer speaker output (-) - terminal 14
    • Right front woofer speaker output (+) - terminal 11
    • Right front woofer speaker output (-) - terminal 12
    • Left rear midrange speaker output (+) - terminal 7
    • Left rear midrange speaker output (-) - terminal 19
    • Right rear midrange speaker output (+) - terminal 8
    • Right rear midrange speaker output (-) - terminal 20
    • Rear subwoofer speaker output (+) - terminal 4
    • Rear subwoofer speaker output (-) - terminal 16
    ⇒If greater than the specified range, test the signal circuit for a short to voltage.
  6. Ignition OFF, test for infinite resistance between the appropriate terminal listed below and ground.
    7. • Front center speaker output (+) - terminal 9
    • Front center speaker output (-) - terminal 21
    • Left front woofer speaker output (+) - terminal 13
    • Left front woofer speaker output (-) - terminal 14
    • Right front woofer speaker output (+) - terminal 11
    • Right front woofer speaker output (-) - terminal 12
    • Left rear midrange speaker output (+) - terminal 7
    • Left rear midrange speaker output (-) - terminal 19
    • Right rear midrange speaker output (+) - terminal 8
    • Right rear midrange speaker output (-) - terminal 20
    • Rear subwoofer speaker output (+) - terminal 4
    • Rear subwoofer speaker output (-) - terminal 16
    ⇒If less than the specified value, test the signal circuit for a short to ground.
  7. Reconnect all harness connectors at the amplifier. Disconnect the harness connector at the appropriate speaker.
  8. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminals listed below and ground.
    9. • Center console speaker- terminal A and B
    • Center I/P speaker- terminal A and B
    • Driver seat left- terminal A and B
    • Driver seat right- terminal A and B
    • Front tweeters- terminal A and B
    • Front speakers- terminal A and B
    • Front subwoofer speakers- terminal D and E
    • Rear compartment speakers - terminal A and B
    • Rear speakers- terminal A and B
    • Passenger seat left speaker - terminal A and B
    • Passenger seat right speaker - terminal A and B
    • Rear subwoofer - terminal Dand E
    ⇒If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the amplifier.
    ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the amplifier.
  9. If all circuits test normal, replace the speaker.

Speaker Circuit Malfunction YQ4 YQ6 YQ7

  1. Disconnect the X1 harness connector at the audio amplifier.
  2. Radio ON, test for 5.0-7.5V between the appropriate audio signal circuit terminal listed below and ground.
    3. • Left front low level (+) - terminal 1
    • Left front low level (-) - terminal 17
    • Right front low level (+) - terminal 2
    • Right front low level (-) - terminal 18
    • Left rear low level (+) - terminal 5
    • Left rear low level (-) - terminal 21
    • Right rear low level (+) - terminal 6
    • Right rear low level (-) - terminal 22
    • Center channel low level (+) - terminal 3
    • Center channel and subwoofer low level audio common (-) - terminal 19
    • Sub woofer low level (+) - 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, connect the X1 harness connector at the audio amplifier.
  4. Disconnect the X2 harness connector at the audio amplifier.
  5. Ignition ON, test for less than 1V between the appropriate speaker signal circuit terminal listed below and ground.
    6. • Front center speaker output (+) - terminal 6
    • Front center speaker output (-) - terminal 18
    • Center console speaker output (+) - terminal 3
    • Center console speaker output (-) - terminal 15
    • Left front speaker output (+) - terminal 7
    • Left front speaker output (-) - terminal 19
    • Left front woofer speaker output (+) - terminal 27
    • Left front woofer speaker output (-) - terminal 35
    • Left front seat left speaker output (+) - terminal 10
    • Left front seat left speaker output (-) - terminal 22
    • Left front seat right speaker output (+) - terminal 23
    • Left front seat right speaker output (-) - terminal 31
    • Right front speaker output (+) - terminal 8
    • Right front speaker output (-) - terminal 20
    • Right front speaker woofer output (+) - terminal 28
    • Right front speaker woofer output (-) - terminal 36
    • Right front seat left speaker output (+) - terminal 9
    • Right front seat left speaker output (-) - terminal 21
    • Right front seat right speaker output (+) - terminal 24
    • Right front seat right speaker output (-) - terminal 32
    • Left rear midrange speaker output (+) - terminal 13
    • Left rear midrange speaker output (-) - terminal 14
    • Left rear shelf speaker output (+) - terminal 4
    • Left rear shelf speaker output (-) - terminal 16
    • Right rear midrange speaker output (+) - terminal 11
    • Right rear midrange speaker output (-) - terminal 12
    • Right rear shelf speaker output (+) - terminal 5
    • Right rear shelf speaker output (-) - terminal 17
    • Rear subwoofer speaker output (+) - terminal 29
    • Rear subwoofer speaker output (-) - terminal 37
    ⇒If greater than the specified range, test the signal circuit for a short to voltage.
  6. Ignition OFF, test for infinite resistance between the appropriate terminal listed below and ground.
    7. • Front center speaker output (+) - terminal 6
    • Front center speaker output (-) - terminal 18
    • Center console speaker output (+) - terminal 3
    • Center console speaker output (-) - terminal 15
    • Left front speaker output (+) - terminal 7
    • Left front speaker output (-) - terminal 19
    • Left front woofer speaker output (+) - terminal 27
    • Left front woofer speaker output (-) - terminal 35
    • Left front seat left speaker output (+) - terminal 10
    • Left front seat left speaker output (-) - terminal 22
    • Left front seat right speaker output (+) - terminal 23
    • Left front seat right speaker output (-) - terminal 31
    • Right front speaker output (+) - terminal 8
    • Right front speaker output (-) - terminal 20
    • Right front speaker woofer output (+) - terminal 28
    • Right front speaker woofer output (-) - terminal 36
    • Right front seat left speaker output (+) - terminal 9
    • Right front seat left speaker output (-) - terminal 21
    • Right front seat right speaker output (+) - terminal 24
    • Right front seat right speaker output (-) - terminal 32
    • Left rear midrange speaker output (+) - terminal 13
    • Left rear midrange speaker output (-) - terminal 14
    • Left rear shelf speaker output (+) - terminal 4
    • Left rear shelf speaker output (-) - terminal 16
    • Right rear midrange speaker output (+) - terminal 11
    • Right rear midrange speaker output (-) - terminal 12
    • Right rear shelf speaker output (+) - terminal 5
    • Right rear shelf speaker output (-) - terminal 17
    • Rear subwoofer speaker output (+) - terminal 29
    • Rear subwoofer speaker output (-) - terminal 37
    ⇒If less than the specified value, test the signal circuit for a short to ground.
  7. Reconnect all harness connectors at the amplifier. Disconnect the harness connector at the appropriate speaker.
  8. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminals listed below and ground.
    9. • Center console speaker- terminal A and B
    • Center I/P speaker- terminal A and B
    • Driver seat left- terminal A and B
    • Driver seat right- terminal A and B
    • Front tweeters- terminal A and B
    • Front speakers- terminal A and B
    • Front subwoofer speakers- terminal D and E
    • Rear compartment speakers - terminal A and B
    • Rear speakers- terminal A and B
    • Passenger seat left speaker - terminal A and B
    • Passenger seat right speaker - terminal A and B
    • Rear subwoofer - terminal D and E
    ⇒If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the amplifier.
    ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the amplifier.
  9. 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 Audio Amplifier and Radio replacement, setup, and programming