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Home >> Chevrolet >> 2006 >> Cobalt LTZ >> Repair and Diagnosis >> External Pages >> Different car >> Section 735 (Lighting Systems) >> Diagnostic Information and Procedures >> Daytime Running Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

Daytime Running Lamps Malfunction

  1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
  2. Connect a test lamp between the control circuit terminal E5 and B+.
  3. Command the DRLs 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 an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Ignition OFF, connect the X2 harness connector at the underhood fuse block.
  5. Disconnect the X3 harness connector at the underhood fuse block.
  6. Connect a test lamp between the control circuit terminal F4 and ground.
  7. Command the DRLs 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 underhood fuse block.
    • If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
    • If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, replace the underhood fuse block.

Ambient Light Sensor Malfunction

  1. Ignition OFF, disconnect the harness connector at the ambient light sensor.
  2. Ignition OFF, scan tool OFF, doors CLOSED, test for less than 10 hms between the low reference circuit terminal B and ground.
    • If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  3. If all circuits test normal, replace the ambient light sensor.
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