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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 54 (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 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.
    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: G101
    2. Test for less than 2 ohms between the test points: Ground circuit terminal G101 & 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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