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Circuit/System Testing

Liftgate Power Open/Close Malfunction

  1. Ignition OFF, disconnect the X2 harness connector at the K39 Liftgate Control Module.Ignition ON
  2. Verify a test lamp illuminates between the B+ circuit terminal 3 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF, remove the test lamp.
    2. Test for infinite resistance between the B+ 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 infinite resistance between the signal circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K39 Liftgate Control Module.
    • Go to next step: If the test lamp illuminates 
  3. Ignition OFF, connect the X2 harness connector at the K39 Liftgate Control Module and disconnect the harness connector at the A23C Liftgate Latch Assembly.Ignition ON
  4. Verify the scan tool Liftgate Latch Pawl Switch parameter is Closed.
    • If not Closed 
    1. Ignition OFF, disconnect the harness connector at the K39 Liftgate Control Module.
    2. Test for infinite resistance between the signal circuit terminal 1 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K39 Liftgate Control Module.
    • Go to next step: If Closed 
  5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 6.
  6. Verify the scan tool Liftgate Latch Pawl Switch parameter is Open
    • If not Open 
    1. Ignition OFF, disconnect the harness connector at the K39 Liftgate Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    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 K39 Liftgate Control Module.
    • Go to next step: If Open 
  7. Verify the scan tool Liftgate Latch Ratchet Switch parameter is Closed.
    • If not Closed 
    1. Ignition OFF, disconnect the harness connector at the K39 Liftgate Control Module.
    2. Test for infinite resistance between the signal circuit terminal 5 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K39 Liftgate Control Module.
    • Go to next step: If Closed 
  8. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the low reference circuit terminal 6.
  9. Verify the scan tool Liftgate Latch Ratchet Switch parameter is Open
    • If not Open 
    1. Ignition OFF, disconnect the harness connector at the K39 Liftgate Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    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 K39 Liftgate Control Module.
    • Go to next step: If Open 
  10. Verify the scan tool Liftgate Latch Sector Switch parameter is Inactive.
    • If not Inactive 
    1. Ignition OFF, disconnect the harness connector at the K39 Liftgate Control Module.
    2. Test for infinite resistance between the signal circuit terminal 2 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K39 Liftgate Control Module.
    • Go to next step: If Inactive 
  11. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 6.
  12. Verify the scan tool Liftgate Latch Sector Switch parameter is Active
    • If not Active 
    1. Ignition OFF, disconnect the harness connector at the K39 Liftgate Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    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 K39 Liftgate Control Module.
    • Go to next step: If Active 
  13. Verify the scan tool Body Control Module Rear Closure Ajar Switch parameter is Inactive
    • If not Inactive 
    1. Ignition OFF, disconnect the harness connector at the K39 Liftgate Control Module.
    2. Test for infinite resistance between the signal circuit terminal 3 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K39 Liftgate Control Module.
    • Go to next step: If Inactive 
  14. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 6.
  15. Verify the scan tool Body Control Module Rear Closure Ajar Switch parameter is Active
    • If not Active 
    1. Ignition OFF, remove the 3 A fused jumper wire, disconnect the harness connector at the K39 Liftgate Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    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 K39 Liftgate Control Module.
    • Go to next step: If Active 
  16. Test or replace the A23C Liftgate Latch Assembly.

Liftgate Erratic Operation

  1. Ignition OFF and all vehicle systems OFF, disconnect the X2 harness connector at the M17 Liftgate Motor Assembly.It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 20 Ω between the low reference circuit terminal 2 and ground.
    • If 20 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the low 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 K39 Liftgate Control Module.
    • Go to next step: If less than 20 Ω 
  3. Test for greater than 11 V between the 12 V reference circuit terminal 1 and ground.
    • If 11 V or less 
    1. Ignition OFF, disconnect the X3 harness connector at the K39 Liftgate Control Module.
    2. Test for infinite resistance between the 12 V reference 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 12 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 K39 Liftgate Control Module.
    • Go to next step: If greater than 11 V 
  4. Test for greater than 11 V between the Position Sensor Signal 1 circuit terminal 3 and ground.
    • If 11 V or less 
    1. Ignition OFF, disconnect the X3 harness connector at the K39 Liftgate Control Module.
    2. Test for infinite resistance between the Position Sensor Signal 1 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 Position Sensor Signal 1 circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K39 Liftgate Control Module.
    • Go to next step: If greater than 11 V 
  5. Test for greater than 11 V between the Position Sensor Signal 2 circuit terminal 4 and ground.
    • If 11 V or less 
    1. Ignition OFF, disconnect the X3 harness connector at the K39 Liftgate Control Module.
    2. Test for infinite resistance between the Position Sensor Signal 2 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 Position Sensor Signal 2 circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K39 Liftgate Control Module.
    • Go to next step: If greater than 11 V 
  6. Replace the M17 Liftgate Motor Assembly.
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