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Home >> Chevrolet >> 2009 >> Impala SS >> Repair and Diagnosis >> External Pages >> Different car >> Section 584 (Lighting Systems) >> Diagnostic Information and Procedures >> Headlamps Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 Chevrolet Monte Carlo and 2007 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

Headlamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the headlamp switch.
  2. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal 8 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool BCM Headlamp Switch parameter is Inactive.
    • 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. Install a 3A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool BCM 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.
  5. Install a 3A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool BCM Auto Hdlp. Disable Sw. parameter cycles between Active and Inactive.
    • If the Auto Hdlp. Disable Sw. parameter does not cycle between the specified values, test the signal circuit for a short to ground, a short to voltage, or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. If all circuits test normal, test or replace the headlamp switch.

Turn Signal/Multifunction Switch Malfunction

  1. Ignition OFF, disconnect the harness connector C2 at the turn signal/multifunction switch.
  2. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal D and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool BCM Flash to Pass Switch parameter is Inactive.
    • If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the BCM.
  4. Verify the scan tool BCM High Beam Select Switch parameter is Inactive.
    • If not the specified value, test the signal circuit terminal E 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 A and ground. Verify the scan tool BCM Flash to Pass 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 E and ground. Verify the scan tool BCM High Beam Select 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.
  7. If all circuits test normal, test or replace the turn signal/multifunction switch.

Low Beam Headlamp Malfunction

  1. Ignition OFF, disconnect the harness connector C4 at the underhood fuse block.
  2. Ignition ON, headlamps off, verify a test lamp does not illuminate between the control circuit terminal H2 and B+.
    • If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
  3. Disconnect the harness connector C3 at the underhood fuse block.
  4. Verify a test lamp does not illuminate between the control circuit terminal B2 and ground.
    • If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the underhood fuse block.
  5. Disconnect the harness connector C2 at the underhood fuse block.
  6. Connect a test lamp between the control circuit terminal A5 and B+.
  7. Command the Low Beams 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.
  8. Ignition OFF, connect the harness connectors at the underhood fuse block. Disconnect the harness connector at the affected low beam headlamp bulb.
  9. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal B and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  10. Connect a test lamp between the control circuit terminal A and ground.
  11. Ignition ON, Command the Low Beams ON and OFF with a scan tool. The scan tool 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, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
    • If the test lamp is OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, replace the affected low beam headlamp bulb.
  12. If all circuits test normal, test or replace the affected low beam headlamp bulb.

High Beam Headlamp Malfunction

  1. Ignition OFF, disconnect the harness connector C2 at the underhood fuse block.
  2. Connect a test lamp between the control circuit terminal C6 and B+.
  3. Ignition ON, Command the High Beams ON and OFF with a scan tool. The scan tool 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 harness connector at the underhood fuse block. Disconnect the harness connector at the affected high beam headlamp bulb.
  5. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal B and ground,
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Connect a test lamp between the control circuit terminal A ground ground.
  7. Ignition ON, Command the High Beams 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, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
    • If the test lamp is OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, replace the affected high beam headlamp bulb.
  8. If all circuits test normal, test or replace the affected high beam headlamp bulb.
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