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Home >> Chevrolet >> 2017 >> SS Automatic Trans >> Repair and Diagnosis (Single Page) >> Engine Performance >> Testing & Diagnosis >> Engine Controls And Fuel - 6.2L (LS3) - Diagnostic Information And Procedures >> Diagnostic Information and Procedures >> DTC P2635 (Chassis Control Module): Fuel Pump Flow Performance >> Circuit/System Testing

Circuit/System Testing

NOTE:

Do not replace the chassis control module based on a history DTC P2635. The DTC P2635 may be stored but that does not indicate a failure of the chassis control module. Refer to Strategy Based Diagnosis for further history DTC diagnostics.

  1. Ignition ON.
  2. Verify DTC P018B, P018C, P018D, P0231, P0232 or P023F is not set.
    • If none of the DTCs are set 
  3. Verify the proper fuel system pressure. Perform the fuel system pressure test, refer to Fuel System Diagnosis .
    • If the fuel system pressure test is not normal 

      Replace the A7 Fuel Pump and Level Sensor Assembly.

    • If the fuel system pressure test is normal 
  4. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the A7 Fuel Pump and Level Sensor Assembly. It may take up to 2 minutes for all vehicle systems to power down.
  5. Test for less than 10 Ω between the low reference circuit terminal 2 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF, disconnect the harness connector at the K38 Chassis Control Module.
    2. Test for less than 2 Ω in the low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K38 Chassis Control Module.
    • If less than 10 Ω 
  6. Connect a test lamp between the control circuit terminal 1 and the low reference circuit terminal 2.
  7. Ignition ON.
  8. 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 K38 Chassis 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 K38 Chassis Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K38 Chassis 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 K38 Chassis Control Module.
    • If the test lamp turns ON and OFF 
  9. All OK.
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