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Home >> Buick >> 2012 >> Regal GS, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 17 (Engine Cooling System) >> Diagnostic Information and Procedures >> Cooling Fan Inoperative >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2011 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the KR20F cooling fan relay.
  2. Test for less than 1Ω between the KR20F Cooling Fan Relay controlled output circuit terminal 87 and ground.
    • If greater than the specified range, test the output circuit for an open/high resistance.
  3. Install the KR20F cooling fan relay.
  4. Disconnect the following KR20 relays.
    • KR20A cooling fan medium speed relay
    • KR20B cooling fan low speed relay
    • KR20D cooling fan high speed relay
    • KR20E cooling fan speed control relay
  5. Ignition ON, connect a test lamp between ground and each of the KR20 relay terminals listed below. The test lamp should illuminate.
    • KR20B cooling fan low speed relay terminal 86
    • KR20E cooling fan speed control relay terminal 86
    • If the test lamp does not illuminate, test the appropriate relay coil B+ circuit for an open/high resistance.
  6. Connect a test lamp between B+ and each of the KR20 relay terminals listed below. Command the cooling fan ON at low speed with a scan tool. The test lamp should illuminate.
    • KR20B cooling fan low speed relay terminal 85
    • KR20E cooling fan speed control relay terminal 85
    • If the test lamp does not illuminate, test the relay coil control circuit for an open/high resistance. If the circuits test normal, test or replace the KR20F relay.
  7. Ignition OFF, install the KR20E cooling fan speed control relay.
  8. Ignition ON, connect a test lamp between ground and the KR20D high speed relay coil B+ circuit terminal 86. Command the cooling fan ON at low speed with a scan tool. The test lamp should illuminate.
    • If the test lamp does not illuminate, test the KR20E relay controlled output circuit and the B+ supply circuit for an open/high resistance. If the circuits test normal, test or replace the KR20E cooling fan speed control relay.
  9. Ignition OFF, install all the previously removed KR20 cooling fan relays.
  10. Ignition OFF, disconnect the harness connector at the G10 Engine Cooling Fan.
  11. Test for less than 1.0Ω between the G10 Engine Cooling Fan ground circuit terminal 1 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  12. Ignition ON, connect a test lamp between ground and each of the G10 cooling fan circuit terminals listed below. Command the cooling fan ON at low, medium, and high speed with a scan tool. The test lamp should illuminate at each terminal as commanded.
    • G10 cooling fan low speed circuit terminal 2
    • G10 cooling fan medium speed circuit terminal 3
    • G10 cooling fan high speed circuit terminal 4
    • If the test lamp does not illuminate, test the appropriate KR20 relay controlled output and B+ supply circuit for a short to ground or for an open/high resistance. If the circuits test normal and the 60 A fuse is OK, test or replace the appropriate KR20 cooling fan relay.
  13. If all of the circuits and relays test normal, test or replace the G10 cooling fan. Replace the fuse if necessary.
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