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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 21 (Engine Controls And Fuel - 4.3L (LV1) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> DTC P0628 >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector : K38 Chassis Control Module
  3. Ignition - On / Vehicle - In Service Mode
  4. Perform the scan tool control function : Fuel Pump Enable - Off

    Verify a test lamp does not turn On between the test points : Control circuit terminal 20 & Ground

    • If the test lamp turns On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector : X1 @ K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points : Control circuit terminal 20 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component : K20 Engine Control Module
    • Go to next step : If the test lamp does not turn On 
  5. Remove - Test Lamp
  6. Perform the scan tool control function : Fuel Pump Enable - On

    Verify the scan tool parameter : Fuel Pump Enable Circuit Low Voltage Test Status = OK

    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector : X1 @ K20 Engine Control Module
    3. Test for infinite resistance between the test points : Control circuit terminal 20 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component : K20 Engine Control Module
    • Go to next step : If the specified state 
  7. Connect a 3 A fused jumper wire between the test points : Control circuit terminal 20 & Ground
  8. Perform the scan tool control function : Fuel Pump Enable - On

    Verify the scan tool parameter : Fuel Pump Enable Circuit Low Voltage Test Status = Malfunction

    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector : X1 @ K20 Engine Control Module
    3. Test for less than 2 ohms between the test points : Control circuit terminal 20 & Terminal 44 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component : K20 Engine Control Module
    • Go to next step : If the specified state 
  9. Test or replace the component : K38 Chassis Control Module
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