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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1920 (Door Lock System And Door Handles) >> Diagnostic Information and Procedures >> Power Door Locks Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

Door Lock Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the driver door lock switch.
  2. Test for less than 1 ohm between the ground circuit terminal 2 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Rear Doors Lock Cmd parameter is Off.
    • If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the BCM.
  4. Verify the scan tool Rear Doors Unlock Cmd parameter is Off.
    • If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the BCM.
  5. Install a 3A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Rear Doors Lock Cmd parameter is On.
    • 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 BCM.
  6. Install a 3A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Rear Doors Unlock Cmd parameter is On.
    • 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 BCM.
  7. If all circuits test normal, test or replace the driver door lock switch.

Door Lock Malfunction

  1. Ignition OFF, disconnect the X1 harness connector at the I/P fuse block.
  2. Test for less than 1 ohm between the ground circuit terminal 57 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 56 and ground.
  4. Ignition ON, command the Lock Rear Doors ON and OFF 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
  5. Connect a test lamp between the control circuit terminal 54 and B+.
  6. Command the doors to UNLOCK by using the driver door lock switch. The test lamp should illuminate when commanding the UNLOCK state.
    • 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 and open/high resistance. If the circuit tests normal, replace the BCM
  7. Connect a test lamp between the control circuit terminal 58 and B+.
  8. Command the doors to UNLOCK by using the driver door lock switch. The test lamp should illuminate when commanding the UNLOCK state.
    • 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 and open/high resistance. If the circuit tests normal, replace the BCM.
  9. Ignition OFF, connect the X1 harness connector at the I/P fuse block and disconnect the harness connector at the appropriate door latch.
  10. Test for less than 1 ohm between the control circuit terminal and ground of the door latch listed below:
    • Driver door latch terminal 2
    • Driver door latch terminal 3
    • LR door latch terminal 2
    • LR door latch terminal 3
    • RR door latch terminal 5
    • RR door latch terminal 6
    • Passenger door latch terminal 5
    • Passenger door latch terminal 6
    • 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 I/P fuse block.
  11. Connect a test lamp between control circuit terminals of the door latch listed below:
    • Driver door latch terminal 2 and terminal 3
    • LR door latch terminal 2 and terminal 3
    • RR door latch terminal 5 and terminal 6
    • Passenger door latch terminal 5 and terminal 6
  12. Ignition ON, command the door latch to LOCK and UNLOCK by using the driver door lock switch. The test lamp should illuminate when commanding the LOCK and UNLOCK states.
    • If the test lamp does not illuminate during either of the commands, test either control circuit for a short to ground. If the circuits test normal, replace the I/P fuse block.
  13. If all circuits test normal, test or replace the door latch.
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