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Home >> Chevrolet >> 2015 >> Cruze LT, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 86 (Engine Controls And Fuel - 1.4L (LUJ LUV) - DTC P0300 To DTC P2635 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Fuel Pump Electrical Circuit Diagnosis (LUJ) >> 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 and all vehicle systems OFF, disconnect the KR23A Fuel Pump Relay. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 86 and ground.
    • If 10 Ω or greater  
    1. Ignition OFF.
    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 less than 10 Ω 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the ignition circuit terminal 30 and ground.
    • If the test lamp does not illuminate and the circuit fuse is OK 
    1. Ignition OFF, remove the test lamp.
    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 OK 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 ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Disconnect the harness connector at the G12 Fuel Pump.
    4. Test for infinite resistance between the output control circuit terminal 87 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, test or replace the G12 Fuel Pump.
    • If the test lamp illuminates 
  5. Verify that a test lamp does not illuminate between the control circuit terminal 85 and ground.
    • If the test lamp illuminates 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
    2. 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, replace the K20 Engine Control Module.
    • If the test lamp does not illuminate 
  6. Remove the test lamp.
  7. Verify the scan tool Fuel Pump Relay Control Circuit Low Voltage Test Status parameter is OK when commanding the Fuel Pump Relay ON.
    • If OK is not displayed 
    1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the 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 OK is displayed 
  8. Install a 3 A fused jumper wire between the control circuit terminal 85 and the ground circuit terminal 86.
  9. Verify the scan tool Fuel Pump Relay Control Circuit Low Voltage Test Status parameter is Malfunction when commanding the Fuel Pump Relay ON.
    • If Malfunction is not displayed 
    1. Ignition OFF, remove the jumper wire, disconnect the harness connector at the K20 Engine Control Module.
    2. 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 Malfunction is displayed 
  10. Verify that a test lamp does not illuminate between the output control circuit terminal 87 and ground.
    • If the test lamp illuminates  

      Repair the short to voltage on the control circuit

    • If the test lamp does not illuminate 
  11. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the G12 Fuel Pump. It may take up to 2 minutes for all vehicle systems to power down.
  12. Test for less than 10 Ω between the G12 Fuel Pump ground circuit terminal 2 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    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 less than 10 Ω 
  13. Connect the harness connector at the G12 Fuel Pump.
  14. Ignition ON, connect a 20 A fused jumper wire between the ignition circuit terminal 30 and the output control circuit terminal 87.
  15. Verify the G12 Fuel Pump is activated.
    • If the G12 Fuel Pump does not activate 
    1. Ignition OFF, remove the jumper wire, disconnect the harness connector at the G12 Fuel Pump.
    2. Test for less than 2 Ω in the output 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 G12 Fuel Pump.
    • If the G12 Fuel Pump activates 
  16. Replace the KR23A Fuel Pump Relay.
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