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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 >> DTC B3125, B3130, or B3135 >> 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.
  1. Ignition OFF, disconnect the X1 harness connector at the I/P fuse block.
  2. Connect a test lamp between the control circuit terminal 56 and ground.
  3. Ignition ON, command the Lock 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.
  4. Connect a test lamp between the control circuit terminal 54 and B+.
  5. Command the Driver Door Unlock 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 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.
  6. Connect a test lamp between the control circuit terminal 58 and B+.
  7. Command the Unlock 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 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.
  8. If all circuits test normal, replace the I/P fuse block.
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