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Home >> Hummer >> 2008 >> H3 Base, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 457 (Lighting System) >> Diagnostic Information and Procedures >> DTC B1457 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2010 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the left headlamp leveling actuator.
  2. Ignition ON, verify that a test lamp illuminates between the low reference circuit terminal 2 and B+.
    • If the test lamp does not illuminate, test the low reference circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the headlamp leveling module.
  3. Ignition OFF, connect a test lamp between the control circuit terminal 4 and the low reference circuit terminal 2.
  4. Ignition ON, headlamps ON, perform the Headlamp Motor Test with a scan tool. The test lamp should turn ON then OFF as the motor test is performed.
    • If the test lamp is always ON, test the control circuit terminal 4 for a short to voltage. If the circuit tests normal, replace the headlamp leveling module.
    • If the test lamp is always OFF, test the control circuit terminal 4 for a short to ground or an open/high resistance. If the circuit tests normal, replace the headlamp leveling module.
  5. If all circuits test normal, replace the left headlamp leveling actuator.
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