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Home >> Chevrolet >> 2020 >> Malibu LS >> Repair and Diagnosis >> External Pages >> Different car >> Section 119 (Active Noise Cancellation System) >> Diagnostic Information and Procedures >> DTC B126F, B1277, B127C, or B127D (without IOR) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the appropriate electrical connector: @ B77 Radio Volume Compensator Interior Noise Microphone
  3. Ignition - On / Vehicle - In Service Mode
  4. Test for 7.8 to 8.8 V between the test points:Signal circuit terminal 2 & Ground
    • If less than 7.8 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector:X3 @ K108 Active Noise Cancellation Module/T3 Audio Amplifier
    3. Test for infinite resistance between the test points:Signal circuit terminal 2 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points:Signal circuit terminal 2 & The other end of the circuit
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component:K108 Active Noise Cancellation Module/T3 Audio Amplifier
    • If greater than 8.8 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector:X3 @ K108 Active Noise Cancellation Module/T3 Audio Amplifier
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points:Signal circuit terminal 2 & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component:K108 Active Noise Cancellation Module/T3 Audio Amplifier
    • Go to next step: If between 7.8 and 8.8 V 
  5. Test for less than 1 V between the test points:Low Reference circuit terminal 1 & Ground
    • If greater than 1 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector:X3 @ K108 Active Noise Cancellation Module/T3 Audio Amplifier
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points:Low Reference circuit terminal 1 & Ground
    5. If 1 V or greater - Repair the short to voltage on the circuit.
    6. If less than 1 V - Replace the component:K108 Active Noise Cancellation Module/T3 Audio Amplifier
    • Go to next step: If less than 1 V 
  6. Ignition/Vehicle & All vehicle systems - Off
  7. Disconnect the electrical connector:X3 @ K108 Active Noise Cancellation Module/T3 Audio Amplifier
  8. Test for infinite resistance between the test points:Low Reference circuit terminal 1 & Ground
    • If less than infinite resistance 

      Repair the short to ground on the circuit.

    • Go to next step: If infinite resistance 
  9. Test for less than 2 ohms between the test points:Low Reference circuit terminal 1 & The other end of the circuit
    • If 2 ohms or greater 

      Repair the open/high resistance in the circuit.

    • Go to next step: If less than 2 ohms 

      Go to next step: Replace the appropriate component:B77 Radio Volume Compensator Interior Noise Microphone

  10. Ignition - On / Vehicle - In Service Mode
  11. Verify that no DTC listed in the DTC Descriptor Category is set.
    • If a related DTC is set 

      Replace the component:K108 Active Noise Cancellation Module/T3 Audio Amplifier

    • Go to next step: If a DTC was not set 
  12. All OK.
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