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Home >> Chevrolet >> 2015 >> Cruze LT, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 57 (Engine Cooling System) >> Diagnostic Information and Procedures >> DTC P0480 or P0481: Cooling Fan Relay (2H0) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2015 Chevrolet Trax and 2015 Buick Encore. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the cooling fan relays listed below:
    • KR20C Cooling Fan Low Speed Relay
    • KR20D Cooling Fan High Speed Relay
    2. NOTE:

    The following test must be performed on each of the relay coil ignition circuits.

  2. Ignition ON, verify that a test lamp illuminates between the relay coil ignition circuit terminal listed below and ground:
    • KR20C Cooling Fan Low Speed Relay terminal 85
    • KR20D Cooling Fan High Speed Relay terminal 85
    • 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 ignition circuit of the appropriate 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, remove the test lamp.
    2. Test for infinite resistance between the relay coil ignition circuits listed below and ground:
      • KR20C Cooling Fan Low Speed Relay terminal 85
      • KR20D Cooling Fan High Speed Relay terminal 85
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance, test all of the appropriate relays for a shorted condition and replace as necessary.
    • If the test lamp illuminates 
  3. Ignition OFF, remove the test lamp, ignition ON.
    4. NOTE:

    The following tests must be performed on the two fan relay control circuits.

  4. Connect a DMM, set on the diode setting, between a control circuit terminal listed below and ground:
    • KR20C Cooling Fan Low Speed Relay terminal 86
    • KR20D Cooling Fan High Speed relay terminal 86
  5. Verify the DMM reading is greater than 2.5 V or displays O.L.
    • If 2.5 V or less 
    1. Ignition OFF, 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. NOTE:

    The following test must be performed on the two fan relay circuits.

  6. Verify the DMM reading is less than 1 V when commanding the Cooling Fan Relays ON with a scan tool.
    • 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 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 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 cooling fan relay.
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