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Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 21 (Power Door Lock System And Release Systems) >> Diagnostic Information and Procedures >> Power Door Locks Inoperative >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

Power Door Lock Malfunction - Front

  1. Ignition OFF, disconnect the harness connector at the inoperative front door latch assembly.
  2. Ignition ON, verify that a test lamp does not illuminate between B+ and the door lock actuator lock control circuit.
    • If the test lamp illuminates, test the lock control circuit for a short to ground. If the circuit tests normal, replace the appropriate door control module.
  3. Ignition ON, verify that a test lamp does not illuminate between B+ and the door lock actuator unlock control circuit.
    • If the test lamp illuminates, test the unlock control circuit for a short to ground. If the circuit tests normal, replace the appropriate door control module.
  4. Ignition ON, verify that a test lamp does not illuminate between ground and the door lock actuator lock control circuit.
    • If the test lamp illuminates, test the lock control circuit for a short to voltage. If the circuit tests normal, replace the appropriate door control module.
  5. Ignition ON, verify that a test lamp does not illuminate between ground and the door lock actuator unlock control circuit.
    • If the test lamp illuminates, test the unlock control circuit for a short to voltage. If the circuit tests normal, replace the appropriate door control module.
  6. Ignition OFF, connect a test lamp between the lock control circuit terminal and unlock control circuit terminal at the door latch harness connector.
  7. Ignition ON, perform the DOOR LOCK/UNLOCK test with a scan tool. The test lamp should turn ON and OFF when performing the DOOR LOCK/UNLOCK test.
    • If the test lamp remains OFF during either of the commands, test for an open/high resistance on either control circuit. If the circuits test normal, replace the appropriate door control module.
  8. If the circuits test normal, test or replace the inoperative door latch assembly.

Power Door Lock Malfunction - Rear

  1. Ignition OFF, disconnect the lock relay.
  2. Test for less than 1.0 ohm of resistance between the ground circuit terminal 2 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Test for less than 1.0 ohm of resistance between the ground circuit terminal 4 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Connect a test lamp between the B+ circuit terminal 1 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 B+ circuit fuse is open, test the control circuit terminal 5 for a short to ground. If the circuit tests normal, test or replace the lock relay.
  5. Connect a test lamp between the control circuit terminal 3 and the ground circuit terminal 4.
  6. Command the rear door locks to LOCK and UNLOCK with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  7. Ignition OFF, disconnect the unlock relay.
  8. Test for less than 1.0 ohm of resistance between the ground circuit terminal 7 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  9. Verify that a test lamp illuminates between the B+ circuit terminal 6 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 B+ circuit fuse is open, test the control circuit terminal 10 for a short to ground. If the circuit tests normal, test or replace the unlock relay.
  10. Verify that a test lamp illuminates between the B+ circuit terminal 8 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  11. Connect a test lamp between the B+ circuit terminal 8 and the control circuit terminal 9.
  12. Command the rear door locks to LOCK and UNLOCK with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  13. Connect the lock relay.
  14. Connect the unlock relay.
  15. Disconnect the harness connector at the inoperative rear door latch assembly.
  16. Ignition OFF, scan tool OFF, test for less than 5.0 ohms of resistance between the lock control circuit terminal B and ground.
    • If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the lock relay.
  17. Test for less than 5.0 ohms of resistance between the unlock control circuit terminal A and ground.
    • If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the unlock relay.
  18. Connect a test lamp between the lock control circuit terminal B and ground.
  19. Command the rear door locks to LOCK with a scan tool. The test lamp should turn ON when commanded.
    • If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the lock relay.
  20. Connect a test lamp between the unlock control circuit terminal A and ground.
  21. Command the rear door locks to UNLOCK with a scan tool. The test lamp should turn ON when commanded.
    • If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the unlock relay.
  22. If all circuits test normal, test or replace the inoperative rear door latch assembly.

Door Open Switch Malfunction - Front

  1. Ignition OFF, disconnect the harness connector at the inoperative front door latch assembly.
  2. Ignition OFF, scan tool OFF, test for less than 10.0 ohms of resistance between the ground circuit and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Door Open Switch parameter is INACTIVE.
    • If the scan tool displays ACTIVE, test the door open switch signal circuit for a short to ground. If the circuit tests normal, replace the appropriate door control module.
  4. Install a 3-A fused jumper wire between the door open switch signal circuit and ground. Verify the scan tool door open switch parameter is ACTIVE.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the appropriate door control module.
  5. If all circuits test normal, test or replace the inoperative door latch assembly.

Door Open Switch Malfunction - Rear

  1. Ignition OFF, disconnect the harness connector at the inoperative rear door latch assembly.
  2. Ignition OFF, scan tool OFF, test for less than 5.0 ohms of resistance between the ground circuit and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition OFF, all other doors closed, verify the interior lights are OFF.
    • If the interior lights are illuminated, test the door open switch signal circuit for a short to ground. If the circuit tests normal, replace the BCM.
  4. Install a 3-A fused jumper wire between the door open switch signal circuit and ground. Verify the interior lights are illuminated.
    • If the interior lights are not illuminated, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the inoperative door latch assembly.
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