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Home >> Buick >> 2016 >> Envision >> Repair and Diagnosis >> External Pages >> Different car >> Section 180 (Cellular System, Entertainment System, And Navigation System) >> Diagnostic Information and Procedures >> DTC B124C: USB 2 Circuit >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2016 Buick LaCrosse. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X1 harness connector at the X83 Auxiliary Audio Input.
  2. Test for less than 10 Ω between the ground circuit terminal 4 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Verify that a test lamp illuminates between the B+ circuit terminal 6 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
    • If the test lamp illuminates 
  4. Verify the USB cable is properly connected at all components and in-line connections, and there is no damage to the cable or connections.
    • If connection problems or cable damage is noted. 

      Perform the appropriate repair or replacement to correct any issues.

    • If no connection problems or cable damage is noted. 
  5. Replace the X83 Auxiliary Audio Input. Connect all harness connectors.
  6. Ignition ON, infotainment system ON.
  7. Connect the EL-50334-20 Multi-Media Interface Tester (MIT) to the X83 Auxiliary Audio Input USB port and select the USB test mode.
  8. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the infotainment system while operating the system to play audio from the test tool.
    • If audio is not heard from the test tool 
    1. Replace the K74 Human Machine Interface Control Module.
    2. Connect the EL-50334-20 Multi-Media Interface Tester (MIT) to the X83 Auxiliary Audio Input USB port and select the USB test mode.
    3. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the infotainment system while operating the system to play audio from the test tool.
      • If audio is not heard from the test tool, replace the USB cable connected to the X83 Auxiliary Audio Input. Verify audio is heard from the test tool. If audio is not heard from the test tool, replace the USB cable connected to the K74 Human Machine Interface Control Module.
      • If audio is heard from the test tool.
    4. All OK
    • If audio is heard from the test tool 
  9. All OK
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