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Home >> Cadillac >> 2015 >> XTS Base >> Repair and Diagnosis (Single Page) >> Engine Performance >> Testing & Diagnosis >> Engine Controls And Fuel - 3.6L (LFX LF3) - DTC P0237 To DTC P2635 And Diagnostic Information And Procedures >> Diagnostic Information and Procedures >> DTC P025A (Chassis Control Module): Fuel Pump Control Module Enable Circuit >> Circuit/System Testing
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Circuit/System Testing

NOTE:

Verify that the fuel tank is not empty. Only perform this diagnostic if there is at least 2 gallons of fuel in the fuel tank. Clear the DTC, and start and run the engine. Verify that the DTC resets before proceeding with the circuit system testing. If the DTC does not reset, refer to diagnostic aids.

  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the K38 Chassis Control Module, ignition ON.
  2. Connect a test lamp between the control circuit terminal 20 and ground.
  3. Verify the test lamp turns On and Off when commanding the fuel pump ON and OFF using the scan tool ECM fuel pump enable control function.
    • If the test lamp is always Off 
    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
    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 K20 Engine Control Module.
    • If the test lamp is always On 
    1. Ignition OFF, 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 turns On and Off 
  4. Test or replace the K38 Chassis Control Module.
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