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Home >> Buick >> 2007 >> Allure CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 19 (Lighting Systems) >> Diagnostic Information and Procedures >> Courtesy Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

Dome Lamp Switch Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the headlamp switch.
  2. Test for less than 10 ohms between the ground circuit terminal 17 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Interior Light Switch parameter is Off.
    • If not the specified value, test the signal circuit terminal 2 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 2 and ground. Verify the scan tool Interior Light Switch parameter is On.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the headlamp switch.

Courtesy Lamp Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate courtesy lamp.
  2. Test for less than 10 ohms between the ground circuit terminal B and ground:
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal listed below and ground:
    • I/P Courtesy Lamp - Terminal A
    • Dome/Reading Lamp - Terminal C
    • Reading Lamps - Terminal C
  4. Ignition ON, command the Interior Lamps 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.
  5. If all circuits test normal, test or replace the appropriate courtesy lamp bulb.

Courtesy Lamp Circuit Malfunction

  1. Driver door open, disconnect the harness connector at the headlamp switch. Verify the courtesy lamps are illuminated.
    • If the courtesy lamps are not illuminated, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the BCM.
  2. Install a 3A jumper wire between the signal circuit terminal 4 and ground. Verify the courtesy lamps are not illuminated.
    • If the courtesy lamps are illuminated, test the signal 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, test or replace the headlamp switch.
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