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Home >> Buick >> 2007 >> Allure CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 19 (Lighting Systems) >> Diagnostic Information and Procedures >> Park, License, and/or Tail 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.

Park Lamp Switch Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the headlamp switch.
  2. Test for less than 10 ohms of resistance between the ground circuit terminal 17 and ground.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Park Lamp Switch parameter is Off.
    • If not the specified value, test the signal circuit terminal 6 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 6 and ground. Verify the scan tool Park Lamp 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.

Park Lamp Relay Circuit Malfunction

  1. Ignition OFF, disconnect the PRK/LAMP relay.
  2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal N1 and ground.
    • If the test lamp does not illuminate, test the control circuit terminal N3 for a short to ground. If the circuit tests normal, test or replace the I/P fuse block.
  3. Verify a test lamp illuminates between the B+ circuit terminal M1 and ground.
    • If the test lamp does not illuminate, test or replace the I/P fuse block.
  4. Install a test lamp between the B+ circuit terminal M1 and the control circuit terminal M3.
  5. Command the Parking 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 terminal M3 for a short to ground. If the circuit tests normal, replace the BCM.
    • If the test lamp is always OFF, test the control circuit terminal M3 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. Ignition OFF, connect the PRK/LAMP relay. Disconnect the harness connector at the left tail lamp.
  7. Install a test lamp between the control circuit terminal A and ground.
  8. Ignition ON, command the Parking Lamps ON with a scan tool. The test lamp should illuminate.
    • If the test lamp does not illuminate, test or replace the PRK/LAMP relay.
  9. If all circuits test normal, test or replace the I/P fuse block.

Front Park Lamp Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative park lamp bulb.
  2. Test for less than 10 ohms of resistance between the appropriate ground circuit terminal and ground:
    • Marker Lamp - Ground circuit terminal B
    • Park/Turn Signal Lamp - Ground circuit terminal C
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Install a test lamp between the appropriate control circuit terminal and ground:
    • Marker Lamp - Control circuit terminal A
    • Park/Turn Signal Lamp - Control circuit terminal B
  4. Ignition ON, command the Parking 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, test or replace the I/P 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, test or replace the I/P fuse block.
  5. If all circuits test normal, test or replace the appropriate park lamp bulb.

Rear Park Lamp Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative park lamp bulb.
  2. Test for less than 10 ohms of resistance between the appropriate ground circuit terminal and ground:
    • Marker Lamp - Ground circuit terminal B
    • Tail/Stop and Turn Signal Lamp - Ground circuit terminal G
    • Tail Lamp Upper or Lower - Ground circuit terminal B
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Install a test lamp between the appropriate control circuit terminal and ground:
    • Marker Lamp - Control circuit terminal A
    • Tail/Stop and Turn Signal Lamp - Control circuit terminal B
    • Tail Lamp Upper or Lower - Control circuit terminal A
  4. Ignition ON, command the Parking 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, test or replace the I/P 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, test or replace the I/P fuse block.
  5. If all circuits test normal, test or replace the appropriate park lamp bulb.

License Lamp Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative license lamp bulb.
  2. Test for less than 10 ohms 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.
  3. Install a test lamp between the control circuit terminal A and ground:
  4. Ignition ON, command the Parking 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, test or replace the I/P 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, test or replace the I/P fuse block.
  5. If all circuits test normal, test or replace the appropriate license lamp bulb.
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