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Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 11 (Engine Controls And Fuel - 6.0L (L96) - DTC P0351 To DTC P2636 And Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> DTC P2636: Fuel Transfer Pump Flow Insufficient >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
  • You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
  • If the fuel level is not between 25 - 50 percent, add 19 L (5 gal) in order to perform this diagnostic procedure. If the fuel level is not within this range, misdiagnosis may occur.
  1. Ignition OFF and all vehicle systems OFF, disconnect the KR23B Fuel Pump Relay - Secondary, ignition ON. It may take up to 2 min for all vehicle systems to power down.
  2. Verify that a test lamp illuminates between the secondary fuel pump relay ignition circuit terminal 30 and ground.
    • If the test lamp does not illuminate and the fuse is good 
    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 not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the 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, test all the components connected to fuse and replace as necessary.
    • Go to next step: If the test lamp illuminates 
  3. Ignition OFF, disconnect the harness connector at the secondary fuel tank fuel pump module.
  4. Test for less than 10 Ω between the secondary fuel pump ground circuit terminal A 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.
    • Go to next step: If less than 10 Ω 
  5. Connect a test lamp between the secondary fuel pump control circuit terminal D and the ground circuit terminal A at the secondary fuel tank fuel pump module harness connector.
  6. Install the KR23B Fuel Pump Relay - Secondary, ignition ON.
  7. Verify the test lamp illuminates when commanding the Fuel Pump Relay 2 ON with a scan tool.
    • If the test lamp does not illuminate 
    1. Ignition OFF, remove the test lamp, disconnect the KR23B Fuel Pump Relay - Secondary.
    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
    3. 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 KR23B Fuel Pump Relay - Secondary.
    • Go to next step: If the test lamp illuminates 
  8. Ignition OFF, remove the test lamp.
  9. Inspect the fuel lines and the secondary fuel tank fuel pump module for a restriction.
    • If a restriction is present 

      Repair as necessary.

    • If a restriction is not present 
  10. Replace the secondary fuel pump.
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