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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 192 (Door Lock Systems & Door Handles) >> Diagnostic Information and Procedures >> Power Liftgate Malfunction >> Circuit/System Testing

Circuit/System Testing

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I/P Switch Inoperative

  1. Ignition OFF, disconnect the harness connector at the I/P switch assembly.
  2. Test for less than 1 ohm between the ground circuit terminal 3 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool LGM Disable Switch parameter is Inactive.
    • If not the specified parameter, test the signal circuit terminal 8 for a short to ground. If the circuit tests normal, replace the LGM.
  4. Verify the scan tool LGM Front Control Switch parameter is Inactive.
    • If not the specified parameter, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the LGM.
  5. Install a 3A fused jumper wire between the signal circuit terminal 8 and ground. Verify the scan tool LGM Disable Switch parameter is Active.
    • If not the specified parameter, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.
  6. Install a 3A fused jumper wire between the signal circuit terminal 7 and ground. Verify the scan tool LGM Front Control Switch parameter is Active.
    • If not the specified parameter, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.
  7. If all circuits test normal, test or replace the I/P switch assembly.

Liftgate Handle Switch Inoperative

  1. Ignition OFF, disconnect the harness connectors at the liftgate exterior switch and liftgate interior switch.
  2. Ignition ON, verify the scan tool Liftgate Handle Sw. Status parameter is Inactive.
    • If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the LGM.
  3. Ignition OFF, connect the harness connector at the exterior liftgate switch.
  4. Ignition ON, observe the scan tool Liftgate Handle Sw. Status parameter while pressing and releasing the exterior liftgate switch, the parameter should change between Active and Inactive.
    • If the parameter does not change, test or replace the exterior liftgate switch.
  5. If all circuits test normal, test or replace the interior liftgate switch.

Latch Assembly Malfunction

  1. Ignition OFF, disconnect the harness connector at the liftgate latch assembly.
  2. Ignition OFF, test for less than 1 ohm between the control circuit terminal 1 and ground.
    • If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the LGM.
  3. Ignition OFF, test for less than 1 ohm between the control circuit terminal 3 and ground.
    • If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuits test normal, replace the LGM.
  4. Connect a test lamp between control circuit terminal 1 and control circuit terminal 3.
  5. Command the liftgate to OPEN and CLOSE with a scan tool. The test lamp should turn ON when commanding the OPEN and CLOSE states.
    • If the test lamp remains OFF during either of the commands, test for a short to ground on both control circuits. If the circuits test normal, replace the LGM.
  6. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal 2 and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the LGM.
  7. Ignition ON, verify the scan tool LGM Latch Pawl Sw. parameter is Inactive
    • If not the specified parameter, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the LGM.
  8. Verify the scan tool LGM Latch Ratchet Sw. parameter is Inactive
    • If not the specified parameter, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the LGM.
  9. Verify the scan tool LGM Latch Sector Sw. parameter is INACTIVE.
    • If not the specified parameter, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the LGM.
  10. Install a 3A fused jumper wire between the signal circuit terminal 5 and low reference circuit terminal 2. Verify the scan tool LGM Latch Pawl Sw. parameter is ACTIVE.
    • If not the specified parameter, test the signal circuit terminal 5 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.
  11. Install a 3A fused jumper wire between the signal circuit terminal 6 and low reference circuit terminal 2. Verify the scan tool LGM Latch Ratchet Sw. parameter is ACTIVE.
    • If not the specified parameter, test the signal circuit terminal 6 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.
  12. Install a 3A fused jumper wire between the signal circuit terminal 4 and low reference circuit terminal 2. Verify the scan tool LGM Latch Sector Sw. parameter is ACTIVE.
    • If not the specified parameter, test the signal circuit terminal 4 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM.
  13. If all circuits test normal, test or replace the liftgate latch assembly.

Power Liftgate Inoperative

  1. Ignition OFF, disconnect the harness connector at the LGM.
  2. Test for less than1 ohm between the ground terminal 6 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 3 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the PWR L/GATE fuse is open, replace the LGM.

Liftgate Closes and Reopens

    IMPORTANT: Check the alignment of the liftgate striker, if the liftgate striker is adjusted too far inboard it could allow the LGM to detect an excess motor current condition and reverse the motor.
  1. Ignition OFF, disconnect the X1 harness connector at the LGM.
  2. Test for infinite resistance between the signal circuit terminal 8 and ground.
    • If less than the specified value, test the signal circuit for a short to ground.
  3. Test for 15K - 25K ohms between the signal circuit terminal 8 and the low reference circuit terminal 16.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the LGM.
    • If not within the specified range, test the signal circuit between the left and right liftgate object sensors and the low reference circuit for an open/high resistance. If the circuits test normal, test or replace the left or right liftgate object sensor.
  4. If all circuits test normal, replace the LGM.
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