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Home >> GMC >> 2018 >> Terrain SL >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Entertainment Systems >> Cellular System, Entertainment System, And Navigation System - Diagnostic Information And Procedures >> Diagnostic Information And Procedures >> DTC B1287: Amplifier Control Signal Circuit >> Circuit/System Testing
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Circuit/System Testing

    NOTE:

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

  1. Ignition OFF/vehicle OFF, disconnect the X1 harness connector at the T3 Amplifier. Ignition ON/vehicle in Service Mode, A11 Radio ON, mute ON.
  2. Test for 7.5 - 8.5 V between the control circuit terminal 3 and ground.
    • If greater than 8.5 V 
    1. Ignition OFF/vehicle OFF, disconnect the X1 harness connector at the A11 Radio. Ignition ON/vehicle in Service Mode.
    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/vehicle OFF, disconnect the X1 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.
      • 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 3 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 Amplifier.
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