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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1904 (Lighting System) >> Diagnostic Information and Procedures >> Headlamps Malfunction >> Circuit/System Testing >> Headlamp Switch Malfunction

Headlamp Switch Malfunction

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 harness connector at the headlamp switch.
  2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 4.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Headlamp Switch parameter is Inactive.
    • If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the BCM.
  4. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Inactive.
    • If not the specified value, test the signal circuit terminal 8 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 6 and ground. Verify the scan tool Headlamp Switch parameter is Active.
    • If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
  6. Install a 3A fused jumper wire between the signal circuit terminal 8 and ground. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Active.
    • If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
  7. If all circuits test normal, test or replace the headlamp switch.
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