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Home >> Buick >> 2021 >> Envision Preferred, AWD >> Repair and Diagnosis (Single Page) >> Body & Frame >> Body, Cab Control Systems >> Vehicle Access System >> Diagnostic Information and Procedures >> DTC B1576 - Liftgate Object Sensor Malfunction >> Circuit/System Testing
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Circuit/System Testing

  1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the B71R Liftgate Side Sensor-Right.
  2. Verify a test lamp illuminates between low reference terminal 2 and B+.
    • If the test lamp does not illuminate 
    1. Test circuit 4656 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    2. Replace the K194 Rear Gate Module.
    • Go to next step: If the test lamp illuminates 
  3. Disconnect the harness connector at the B71L Liftgate Side Sensor - Left.
  4. Ignition ON, test for 4.8 - 5.2 V between the 5 V reference circuit terminal 1 and ground.
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the harness connector at the K194 Rear Gate Module.
    2. Test for infinite resistance between the 5 V reference circuit 4654 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 5 V reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K194 Rear Gate Module.
    • If greater than 5.2 V 
    1. Ignition OFF, disconnect the harness connector at the K194 Rear Gate Module, Ignition ON.
    2. Test for less than 1 V between the 5 V reference circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K194 Rear Gate Module.
    • Go to next step: If between 4.8 - 5.2 V 
  5. Test for less than 2 Ω between the signal circuit terminal 1 and the signal circuit terminal 2 @ signal circuit 4655
    • If 2 Ω or greater 

      Replace the signal circuit 4655.

    • Go to next step: If less than 2 Ω 
  6. Test or replace the appropriate B71 Liftgate Side Sensor
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