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Home >> Buick >> 2021 >> Envision Preferred, AWD >> Repair and Diagnosis >> Body & Frame >> Body, Cab Control Systems >> Vehicle Access System >> Diagnostic Information and Procedures >> DTC B1574 or B1575 - Liftgate Interior Release Open/Close Switch Malfunction >> Circuit/System Testing

Circuit/System Testing

Test 1

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector: S45B Liftgate Control Switch - Interior
  3. Verify a test lamp illuminates between ground circuit terminal 1 and B+.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on circuit 1550 or the ground connection.
    • Go to next step: If the test lamp illuminates 
  4. Ignition - On/Vehicle - In Service Mode
  5. Ignition ON/vehicle in service mode, test for 7 V - 8 V between signal circuit terminal 4 and ground.
    • If less than 7 V 
    1. Test circuit 4652 for a short to ground.
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Test circuit 4652 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.
    3. Replace the K9 Body Control Module.
    • If greater than 8 V 
    1. Test circuit 4652 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the K9 Body Control Module.
    • Go to next step: If between 7 V - 8 V 
  6. Test or replace the component: S45B Liftgate Control Switch - Interior

Test 2

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector: S45B Liftgate Control Switch - Interior
  3. Ignition - On/Vehicle - In Service Mode
  4. Verify the scan tool Rear Gate Module Rear Gate Mode Switch parameter is 2 V
    • If not 2 V 
    1. Test the circuit 4653 for a short to ground
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Replace the K194 Rear Gate Module.
    • Go to next step: If 2 V 
  5. Install a 3 A fused jumper wire between the signal circuit terminal 3 and ground.
  6. Verify the scan tool parameter is now 0 V.
    • If not 0 V and the 3 A fuse is OK 
    1. Test the circuit 4653 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
    • If not 0 V and the 3 A fuse is open 
    1. Test the circuit 4653 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the K194 Rear Gate Module.
    • Go to next step: If 0 V 
  7. Test or replace the component: S45B Liftgate Control Switch - Interior
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