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Tahoe / Yukon Service Manual

Speaker Malfunction (IOK)

Cellular, Entertainment, and Navigation | Diagnostic Information and Procedures | Document ID: 5199326 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 provide an overview of each diagnostic category. Circuit/System Description The audio amplifier is a participant on the Ethernet bus. The audio amplifier receives audio signals and control information from the Radio. The Amplifier receives battery power and ground from the vehicle harness, and also communicates on GMLAN Each of the audio output channel circuits (+) and (−), at the audio amplifier have a DC bias voltage that is approximately 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. Diagnostic Aids Improper speaker mounting or loose trim may cause an audible buzz, distortion or vibration. Inspect the appropriate speaker and the surrounding interior trim for proper and secure mounting. The EL-50334-6 Audio System Diagnostic CD contains audio tracks that can be used to duplicate and isolate such concerns. Tracks 11 and 12 contain audio sweep tones for testing for speaker and grill rattles. If the speaker or surrounding interior trim is found to be loose or improperly secured, correctly secure the item. The test tones on the CD may be copied to a USB drive or other device to use during testing. Some audio output circuits are connected to more than one speaker, dependant on vehicle equipment. It may be necessary to disconnect one or more speakers during testing of some circuits. Reference Information Schematic Reference Radio/Navigation System Schematics Connector End View Reference Component Connector End Views 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 Special Tools EL-50334-50 USB Cable and Adapter Kit Circuit/System Verification

  1. Ignition ON/Vehicle in Service Mode. Infotainment system ON, mute OFF.
  2. Verify clear audio is heard from each speaker, adjusting fade and balance controls to test each speaker individually. ⇒ If audio is inoperative from one or more speakers, or the audio emitted is not clear Refer to Circuit/System Testing. ⇓ If clear audio is heard from all speakers
  3. All OK. Circuit/System Testing
  4. Ignition OFF, disconnect the harness connector at the appropriate P19 Speaker.
  5. Ignition On/Vehicle in Service Mode. Infotainment system ON, mute OFF.
  6. Test for 5–7 V between the appropriate signal circuit terminals listed below and ground. door, I/P speakers, surround audio, and subwoofer (-) circuit terminal 1 door, I/P speakers, surround audio, and subwoofer (+) circuit terminal 2 ⇒ If less than 5 V 3.1. Ignition OFF, disconnect the X1 and X2 harness connectors at the T3 Audio Amplifier. 3.2. Test the appropriate circuit for a short to ground. ⇒ If a short to ground is found, repair the circuit fault. ⇓ If a short to ground is not found 3.3. Test the appropriate circuit for an open/high resistance. ⇒ If an open/high resistance is found, repair the circuit fault. ⇓ If an open/high resistance is not found 3.4. Replace the T3 Audio Amplifier ⇒ If greater than 7 V 3.1. Ignition OFF, disconnect the X1 and X2 harness connectors at the T3 Audio Amplifier. Ignition On/Vehicle in Service Mode. 3.2. Test the appropriate circuit for a short to voltage: ⇒ If a short to voltage is found, repair the circuit fault. ⇓ If a short to voltage is not found 3.3. Replace the T3 Audio Amplifier ⇓ If 5–7 V
  7. Disconnect the appropriate harness connector at the T3 Audio Amplifier
  8. Test for infinite resistance between signal circuit terminal 1 and signal circuit terminal 2 at the appropriate P19 Speaker. ⇒ If less than infinite resistance Repair the short between the two signal circuits. ⇓ If infinite resistance
  9. Test or replace the P19 Speaker. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Speaker Replacement Reference Control Module References for audio amplifier replacement, programming, and setup.