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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 22 (Engine Controls And Fuel - 2.8L (LWN) Diesel - Diagnostic Information And Procedures (2 Of 3)) >> Diagnostic Information and Procedures >> DTC P0627-P0629 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Remove the component : KR23A Fuel Pump Relay
  3. Test for less than 10 ohms between the test points : Ground circuit terminal 86 & Ground
    • If 10 ohms or greater 
    1. Disconnect the ground connection : @ The other end of the circuit
    2. Test for less than 2 ohms between the test points : Ground & Terminal 86
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step : If less than 10 ohms 
  4. Ignition - On / Vehicle - In Service Mode
  5. Verify a test lamp does not turn On between the test points : Control circuit terminal 85 & 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 85 @ Relay Socket & 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 
  6. Remove - Test Lamp
  7. Perform the scan tool control function : Fuel Pump Relay - On

    Verify the scan tool parameter : Fuel Pump Relay Control 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 85 @ Relay Socket & 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 
  8. Connect a 3 A fused jumper wire between the test points : Control circuit terminal 85 @ Relay Socket & Ground circuit terminal 86 @ Relay Socket
  9. Perform the scan tool control function : Fuel Pump Relay - On

    Verify the scan tool parameter : Fuel Pump Relay Control 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 85 @ Relay Socket & Terminal 50 @ 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 
  10. Test or replace the component : KR23A Fuel Pump Relay
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