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Home >> Chevrolet >> 2015 >> Cruze LT, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 14 (Engine Controls And Fuel - 2.0L (LUZ) Diesel - DTC P2122 To DTC P2689 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P2687-P2689: Fuel Heater Relay Control Circuit >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition OFF.
  2. Disconnect the KR22 Fuel Heater Relay.
  3. Ignition ON.
  4. Verify that a test lamp does not illuminate between the fuel heater relay coil control circuit terminal 85 and ground.
    • If the test lamp illuminates 
    1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
    2. Ignition ON, test for less than 1 V between the fuel heater relay coil control circuit terminal 85 and ground.
      • If 1 V or greater, repair the short to voltage in the circuit.
      • If less than 1 V, replace the K20 Engine Control Module.
    • If the test lamp does not illuminate 
  5. Verify that a test lamp illuminates between the fuel heater relay coil ignition circuit terminal 86 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the 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 does not illuminate and the circuit fuse is open 
    1. Ignition OFF.
    2. Test for infinite resistance between the ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, verify there is voltage at the circuit fuse.
    • If the test lamp illuminates 
  6. Connect a test lamp between the control circuit terminal 85 and the ignition circuit terminal 86.
  7. Verify the test lamp turns ON and OFF when Commanding the Fuel Heater Relay ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
    2. Ignition ON, Test for less than 1 V between the 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 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 the test lamp is always ON 
    1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the fuel heater relay coil control circuit terminal 85 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 test lamp turns ON and OFF 
  8. Test or replace the KR22 Fuel Heater Relay.
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