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Home >> Buick >> 2007 >> Allure CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 52 (Engine Cooling System) >> Diagnostic Information and Procedures >> DTC P0480, P0481, P0691, P0692, P0693, or P0694 (3.6L LY7) >> 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.
  1. Ignition OFF, disconnect all three cooling fan relays.
    2. IMPORTANT: The following test must be performed on all three fan relay circuits.
  2. Ignition ON, verify that a test lamp illuminates between ground and the relay coil B+ circuit terminal listed below:
    • Low speed fan 1 relay terminal A19
    • High speed fan 3 relay terminal K19
    • Series/parallel fan 2 relay terminal K15
    • If the test lamp does not illuminate, test the relay coil B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay coil B+ circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
    3. IMPORTANT: The following test must be performed on all three fan relay circuits.
  3. Test for 2.6-4.6 volts between ground and the relay coil control circuit terminal listed below:
    • Low speed fan 1 relay terminal C18
    • High speed fan 3 relay terminal M18
    • Series/parallel fan 2 relay terminal M14
    • If less than the specified range, test the relay coil control circuit for an open/high resistance or for a short to ground. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the relay coil control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
    4. IMPORTANT: The following test must be performed on all three fan relay circuits.
  4. Connect a test lamp between the relay coil control circuit and the relay coil ignition circuit terminals listed below:
    • Low speed fan 1 relay terminal C18 and terminal A19
    • High speed fan 3 relay terminal M18 and terminal K19
    • Series/parallel fan 2 relay terminal M14 and terminal K15
  5. Command the fan relay 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 OFF, replace the ECM.
  6. If all circuits test normal, test or replace the relay.
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