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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 >> Power Liftgate Malfunction >> Circuit/System Testing

Circuit/System Testing

Test 1

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: E7AC Rear License Plate Lamp Module
  3. Test for less than 10 ohms between the test points: Ground circuit terminal 1 & Ground
    • If 10 ohms or greater 
    1. Ground Connection - Disconnect
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 1 @ Component harness & Ground Connection
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  4. Ignition ON.
  5. Test for greater than 7 V between the signal circuit terminal 3 and ground.
    • If 7 V or less 
    1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module
    2. Test for infinite resistance between the signal 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 signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module
    • Go to next step: If greater than 7 V 
  6. Replace the component: E7AC Rear License Plate Lamp Module

Test 2

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: B70 Liftgate Close Switch
  3. Verify a test lamp turns On between the test points: Low Reference terminal 1 & B+
    • If the test lamp does not turn On 
    1. Disconnect the electrical connector: K194 Rear Gate Module
    2. Test for less than 2 ohms between the test points: Low Reference terminal 1 @ Component harness & Terminal 10 X4 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K194 Rear Gate Module
    • Go to next step: If the test lamp turns On 
  4. Ignition - On/Vehicle - In Service Mode
  5. Verify the scan tool parameter: Rear Gate Close Switch = Inactive
    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K194 Rear Gate Module
    3. Test for infinite resistance between the test points: Signal circuit terminal 3 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: K194 Rear Gate Module
    • Go to next step: If the specified state 
  6. Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 3 & Low Reference terminal 1
  7. Verify the scan tool parameter: Rear Gate Close Switch = Active
    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: K194 Rear Gate Module
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Signal circuit terminal 3 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 ohms between the test points: Signal circuit terminal 3 @ Component harness & Terminal 16 X4 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K194 Rear Gate Module
    • Go to next step: If the specified state 
  8. Test or replace the component: B70 Liftgate Close Switch

Test 3

  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 4

  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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