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Home >> Buick >> 2007 >> Allure CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 19 (Lighting Systems) >> Diagnostic Information and Procedures >> Turn Signal Lamps and/or Indicators 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.

Turn Signal Switch Circuit Malfunction

  1. Ignition OFF, disconnect the X2 harness connector at the turn signal multifunction lever.
  2. Test for less than 5 ohms between the ground circuit terminal G 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 Left Turn Signal parameter is Off.
    • If not the specified value, test the signal circuit terminal F for a short to ground. If the circuit tests normal, replace the BCM.
  4. Verify the scan tool BCM Right Turn Signal parameter is Off.
    • If not the specified value, test the signal circuit terminal H 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 F and the ground circuit terminal A. Verify the scan tool BCM Left Turn Signal 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.
  6. Install a 3A fused jumper wire between the signal circuit terminal H and the ground circuit terminal A. Verify the scan tool BCM Right Turn Signal 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.
  7. If all circuits test normal, test or replace the turn signal multifunction lever.

Turn Signal Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate turn signal lamp bulb.
  2. Test for less than 10 ohms between the ground circuit terminal C (Front) or G (Rear) and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Install a test lamp between the signal circuit terminal A and ground.
  4. Ignition ON, command the appropriate turn signal lamp ON and OFF with a scan tool. The appropriate turn signal lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    • If the test lamp is always OFF, test the signal 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 turn signal lamp bulb.
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