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Home >> GMC >> 2019 >> Terrain SL >> Repair and Diagnosis >> External Pages >> Different car >> Section 190 (Cellular, Entertainment, And Navigation System) >> Diagnostic Information and Procedures >> DTC B186C >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2021 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE:

    To prevent misdiagnosis, the door chime must be OFF during testing. Ensure the driver door latch is closed during testing.

  1. Ignition OFF, disconnect the X2 harness connector at the T3 Audio Amplifier. Ignition ON, A11 Radio ON, mute ON.
  2. Test for 7.5 - 8.5 V between the control circuit terminal 14 and ground.
    • If greater than 8.5 V 
    1. Ignition OFF, disconnect the X2 harness connector at the A11 Radio. Ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the A11 Radio.
    • If less than 7.5 V 
    1. Ignition OFF, disconnect the X2 harness connector at the A11 Radio.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the A11 Radio.
    • Go to next step: If between 7.5 - 8.5 V 
  3. A11 Radio ON, mute OFF.
  4. Test for less than 1 V between the control circuit terminal 14 and ground.
    • If 1 V or greater 

      Replace the A11 Radio.

    • Go to next step: If less than 1 V 
  5. Test or replace the T3 Audio Amplifier.
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