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Circuit/System Testing

WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect all of the KR20 cooling fan relays.
    2. NOTE: The jumper wire completes the right side fan ground circuit. Leave this jumper in place for the remainder of this procedure.
  2. Connect a 30 A fused jumper between the KR20E relay switch circuit terminal 30 and the ground circuit terminal 87.
    3. NOTE: The following test must be performed on both the high speed fan relay circuit and the low speed fan relay circuit.
  3. Ignition ON, verify that a test lamp illuminates between ground and the relay switched B+ circuit terminal listed below:
    • KR20C COOL FAN 1 Relay Terminal 30
    • KR20D COOL FAN 2 Relay Terminal 30
    • If the test lamp does not illuminate, test the appropriate relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the appropriate KR20 relay.
    4. NOTE: The following test must be performed first on the high speed fan relay circuit and next on the low speed fan relay circuit. Leave the jumper connected to the low speed fan relay circuit for the next test.
  4. Connect a 30 A fused jumper between the KR20 cooling fan relay circuit terminals listed below. Verify the appropriate fan is activated.
    • KR20D COOL FAN 2 Relay Terminals 87 and 30
    • KR20C COOL FAN 1 Relay Terminals 87 and 30
    • If the corresponding cooling fan does not activate, test the relay controlled output circuit and the cooling fan ground circuit for an open/high resistance. If the circuits tests normal, replace the appropriate G10 cooling fan.
    • If the corresponding cooling fan activates, replace the appropriate KR20 cooling fan relay.
  5. Install the KR20E speed control COOL FANS relay. Verify both fans activate at low speed.
    • If both fans do not activate, test the relay controlled output circuit terminal 87A of the KR20E relay for a short to ground or an open/high resistance.
  6. If all circuits test normal, test or replace the KR20E cooling fan speed control relay.
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