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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 104 (Engine Controls And Fuel - 6.0L (L96 LC8) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> DTC P0628 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
  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 2 & 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 @ Component harness & Terminal 28 @ 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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