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Home >> Chevrolet >> 2015 >> Cruze LT, Automatic Trans >> Repair and Diagnosis >> Engine Mechanical >> Cooling System (Mechanical) >> Engine Cooling System >> Diagnostic Information and Procedures >> Cooling Fan Inoperative (LUW, LUV or LWE) >> Circuit/System Testing >> Low, Medium or High Speed Inoperative

Low, Medium or High Speed Inoperative

  1. Disconnect the following cooling fan relays, ignition ON:
    • KR20C Cooling Fan Low Speed Relay
    • KR20D Cooling Fan High Speed Relay
    • KR20E Cooling Fan Speed Control Relay
    • KR20F Cooling Fan Relay
    • KR20P Cooling Fan Medium Speed Relay
  2. Verify a test lamp illuminates between ground and each of the cooling fan relay B+ circuit terminals listed below:
    • KR20C Cooling Fan Low Speed Relay terminal 30/3
    • KR20D Cooling Fan High Speed Relay terminal 87/5
    • KR20P Cooling Fan Medium Speed Relay terminal 87/5
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2 Ω in the appropriate relay B+ circuit, end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF, disconnect the harness connector at the G10 Cooling Fan Motor.
    2. Test for infinite resistance between the appropriate relay controlled output circuit terminal listed below and ground:
      • KR20C Cooling Fan Low Speed Relay terminal 87/5
      • KR20D Cooling Fan High Speed Relay terminal 30/3
      • KR20P Cooling Fan Medium Speed Relay terminal 30/3
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance, test or replace the G10 Cooling Fan Motor, replace the fuse as necessary.
    • If the test lamp illuminates 
  3. Verify a test lamp illuminates between the KR20F Cooling Fan Relay output circuit terminal 87/5 and B+.
    • If the test lamp does not illuminate 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2 Ω in the ground circuit, end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If the test lamp illuminates 
  4. Ignition OFF, Install the KR20F Cooling Fan Relay, ignition ON.
  5. Verify a test lamp illuminates between ground and each of the cooling fan relay terminals listed below:
    • KR20C Cooling Fan Low Speed Relay terminal 85/2
    • KR20E Cooling Fan Speed Control Relay terminal 86/1 and 30/3
    • If the test lamp does not illuminate at each terminal 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2 Ω in the appropriate relay ignition circuit, end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp illuminates at each terminal 
  6. Command the cooling fan ON at low speed with a scan tool.
  7. Verify a test lamp illuminates between B+ and each of the KR20 Cooling Fan Relay terminals listed below:
    • KR20C Cooling Fan Low Speed Relay terminal 86/1
    • KR20E Cooling Fan Speed Control Relay terminal 85/2
    • If the test lamp does not illuminate 
    1. Ignition OFF, remove the test lamp and disconnect the KR20F Cooling Fan Relay.
    2. Test for less than 2 Ω between the KR20F Cooling Fan Relay terminal 30/3 and the relay control circuit terminals listed below:
      • KR20C Cooling Fan Low Speed Relay terminal 86/2
      • KR20E Cooling Fan Speed Control Relay terminal 85/2
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the KR20F Cooling Fan Relay.
    • If the test lamp illuminates 
  8. Ignition OFF, install the KR20E Cooling Fan Speed Control Relay, Ignition ON.
  9. Command the cooling fan ON at low speed with a scan tool.
  10. Verify a test lamp illuminates between ground and the KR20D High Speed Relay ignition circuit terminal 86/1.
    • If the test lamp does not illuminate 
    1. Ignition OFF, remove the test lamp and disconnect the KR20E Cooling Fan Speed Control Relay.
    2. Test for less than 2 Ω between the KR20D High Speed Relay terminal 86/1 and KR20E Cooling Fan Speed Control Relay 87/5
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the KR20E Cooling Fan Speed Control Relay.
    • If the test lamp illuminates 
  11. Ignition OFF, install all of the previously removed KR20 Cooling Fan Relays. Disconnect the harness connector at the G10 Cooling Fan Motor, ignition ON.
  12. Command the cooling fan ON at high speed with a scan tool.
  13. Verify a test lamp illuminates between ground and each of the G10 Cooling Fan Motor circuit terminals listed below:
    • 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 at each terminal 
    1. Ignition OFF, remove the test lamp.
    2. Disconnect the appropriate relay from the list below:
      • KR20C Cooling Fan Low Speed Relay
      • KR20D Cooling Fan High Speed Relay
      • KR20P Cooling Fan Medium Speed Relay
    3. Test for less than 2 Ω in the relay controlled output circuit, end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, test or replace the relay.
    • If the test lamp illuminate at each terminal 
  14. Test or replace the G10 Cooling Fan Motor.
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