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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 >> DTC P0480, P0481, P0691, P0692, P0693 or P0694: Cooling Fan Relays (LUW, LUV or LWE) >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the KR20 cooling fan relays listed below:
    • KR20F Cooling Fan Relay
    • KR20P Cooling Fan Medium Speed Relay
    • KR20D Cooling Fan High Speed Relay
  2. Ignition ON, verify that a test lamp illuminates between ground and the relay coil ignition circuit terminal listed below:
    NOTE: The following test must be performed on each of the relay coil ignition circuits.
    • KR20F Cooling Fan Relay terminal 85/2
    • KR20P Cooling Fan Medium Speed Relay terminal 86/1
    • If the test lamp does not illuminate and the fuse is good 
    1. Ignition OFF and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down.
    2. Test for less than 2 Ω in the ignition circuit of the appropriate KR20 Cooling Fan Relay, 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 and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down.
    2. Test for infinite resistance between the relay coil ignition circuits listed below and ground:
      • KR20F Cooling Fan Relay terminal 85/2
      • KR20D Cooling Fan High Speed Relay terminal 86/1
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance, test all of the appropriate KR20 Cooling Fan Relays for a short and replace as necessary.
    • If the test lamp illuminates 
  3. Ignition OFF, remove the test lamp, ignition ON.
  4. Connect a DMM, set on the diode setting, between a control circuit terminal listed below and ground:
    NOTE: The following tests must be performed on all three fan relay control circuits.
    • KR20F Cooling Fan Relay terminal 86/1
    • KR20P Cooling Fan Medium Speed Relay terminal 85/2
    • KR20D Cooling Fan High Speed Relay terminal 85/2
  5. Verify the DMM reading is greater than 2.5 V or displays O.L.
    • If 2.5 V or less 
    1. Ignition OFF and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down. Disconnect the X1 harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the appropriate relay coil control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K20 Engine Control Module.
    • If greater than 2.5 V or displays O.L. 
  6. Verify the DMM reading is less than 1 V when commanding the Cooling Fan Relays ON with a scan tool.
    NOTE: The following test must be performed on all three fan relay circuits.
    • If 1 V or greater 
    1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module, ignition ON.
    2. Test for less than 1 V between the appropriate KR20 Cooling Fan Relay control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V.
    3. Ignition OFF.
    4. Test for less than 2 Ω in the appropriate KR20 Cooling Fan Relay control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
    • If less than 1 V 
  7. Test or replace the appropriate KR20 Cooling Fan Relay.
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