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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 24 (Engine Controls And Fuel - 2.8L (LWN) Diesel - Diagnostic Information And Procedures (1 Of 3)) >> Diagnostic Information and Procedures >> DTC P0201-P0204, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P1248, P1249, P124A, P124B, P2147, P2148, P2150, or P2151 >> Circuit/System Testing

Circuit/System Testing

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

Test 1

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector : X2 @ K20 Engine Control Module
  3. Test for infinite resistance between the test points :
    • {Q17A Fuel Injector 1} Control circuit terminal 4 & Ground
    • {Q17B Fuel Injector 2} Control circuit terminal 1 & Ground
    • {Q17C Fuel Injector 3} Control circuit terminal 2 & Ground
    • {Q17D Fuel Injector 4} Control circuit terminal 3 & Ground
    • If less than infinite resistance 
    1. Disconnect the appropriate electrical connector : Q17 Fuel Injector
    2. Test for infinite resistance between the test points :
      • {Q17A Fuel Injector 1} Control circuit terminal 4 @ Control module harness & Ground
      • {Q17B Fuel Injector 2} Control circuit terminal 1 @ Control module harness & Ground
      • {Q17C Fuel Injector 3} Control circuit terminal 2 @ Control module harness & Ground
      • {Q17D Fuel Injector 4} Control circuit terminal 3 @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step : If infinite resistance
    3. Test for infinite resistance between the test points :
      • {Q17A Fuel Injector 1} Control circuit terminal 8 @ Control module harness & Ground
      • {Q17B Fuel Injector 2} Control circuit terminal 5 @ Control module harness & Ground
      • {Q17C Fuel Injector 3} Control circuit terminal 6 @ Control module harness & Ground
      • {Q17D Fuel Injector 4} Control circuit terminal 7 @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component : Q17 Fuel Injector
    • Go to next step : If infinite resistance 
  4. Ignition - On / Vehicle - In Service Mode
  5. Test for less than 1 V between the test points :
    • {Q17A Fuel Injector 1} Control circuit terminal 4 & Ground
    • {Q17B Fuel Injector 2} Control circuit terminal 1 & Ground
    • {Q17C Fuel Injector 3} Control circuit terminal 2 & Ground
    • {Q17D Fuel Injector 4} Control circuit terminal 3 & Ground
    • If 1 V or greater 
    1. Disconnect the appropriate electrical connector : Q17 Fuel Injector
    2. Test for less than 1 V between the test points :
      • {Q17A Fuel Injector 1} Control circuit terminal 4 @ Control module harness & Ground
      • {Q17B Fuel Injector 2} Control circuit terminal 1 @ Control module harness & Ground
      • {Q17C Fuel Injector 3} Control circuit terminal 2 @ Control module harness & Ground
      • {Q17D Fuel Injector 4} Control circuit terminal 3 @ Control module harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Repair the short to voltage on the circuit :
      • {Q17A Fuel Injector 1} Control circuit terminal 8
      • {Q17B Fuel Injector 2} Control circuit terminal 5
      • {Q17C Fuel Injector 3} Control circuit terminal 6
      • {Q17D Fuel Injector 4} Control circuit terminal 7
    • Go to next step : If less than 1 V 
  6. Ignition/Vehicle - Off
  7. Disconnect the appropriate electrical connector : Q17 Fuel Injector
  8. Test for less than 2 ohms between the test points :
    • {Q17A Fuel Injector 1} Control circuit terminal 4 @ Control module harness & Control circuit terminal 1 @ Component harness
    • {Q17A Fuel Injector 1} Control circuit terminal 8 @ Control module harness & Control circuit terminal 2 @ Component harness
    • {Q17B Fuel Injector 2} Control circuit terminal 1 @ Control module harness & Control circuit terminal 1 @ Component harness
    • {Q17B Fuel Injector 2} Control circuit terminal 5 @ Control module harness & Control circuit terminal 2 @ Component harness
    • {Q17C Fuel Injector 3} Control circuit terminal 2 @ Control module harness & Control circuit terminal 1 @ Component harness
    • {Q17C Fuel Injector 3} Control circuit terminal 6 @ Control module harness & Control circuit terminal 2 @ Component harness
    • {Q17D Fuel Injector 4} Control circuit terminal 3 @ Control module harness & Control circuit terminal 1 @ Component harness
    • {Q17D Fuel Injector 4} Control circuit terminal 7 @ Control module harness & Control circuit terminal 2 @ Component harness
    • If 2 ohms or greater 

      Repair the open/high resistance in the circuit.

    • Go to next step : If less than 2 ohms 
  9. Verify a condition does not exist with the component : Q17 Fuel Injector - Refer to : Component Testing
    • If a condition exists 

      Replace the component : Q17 Fuel Injector

    • Go to next step : If no condition exists 
  10. Replace the component : K20 Engine Control Module

Test 2

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector : X2 @ K20 Engine Control Module
  3. Test for infinite resistance between the test points :
    • {Q17A Fuel Injector 1} Control circuit terminal 4 & Ground
    • {Q17B Fuel Injector 2} Control circuit terminal 1 & Ground
    • {Q17C Fuel Injector 3} Control circuit terminal 2 & Ground
    • {Q17D Fuel Injector 4} Control circuit terminal 3 & Ground
    • If less than infinite resistance 
    1. Disconnect the appropriate electrical connector : Q17 Fuel Injector
    2. Test for infinite resistance between the test points :
      • {Q17A Fuel Injector 1} Control circuit terminal 4 @ Control module harness & Ground
      • {Q17B Fuel Injector 2} Control circuit terminal 1 @ Control module harness & Ground
      • {Q17C Fuel Injector 3} Control circuit terminal 2 @ Control module harness & Ground
      • {Q17D Fuel Injector 4} Control circuit terminal 3 @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step : If infinite resistance
    3. Test for infinite resistance between the test points :
      • {Q17A Fuel Injector 1} Control circuit terminal 8 @ Control module harness & Ground
      • {Q17B Fuel Injector 2} Control circuit terminal 5 @ Control module harness & Ground
      • {Q17C Fuel Injector 3} Control circuit terminal 6 @ Control module harness & Ground
      • {Q17D Fuel Injector 4} Control circuit terminal 7 @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component : Q17 Fuel Injector
    • Go to next step : If infinite resistance 
  4. Ignition - On / Vehicle - In Service Mode
  5. Test for less than 1 V between the test points :
    • {Q17A Fuel Injector 1} Control circuit terminal 4 & Ground
    • {Q17B Fuel Injector 2} Control circuit terminal 1 & Ground
    • {Q17C Fuel Injector 3} Control circuit terminal 2 & Ground
    • {Q17D Fuel Injector 4} Control circuit terminal 3 & Ground
    • If 1 V or greater 
    1. Disconnect the appropriate electrical connector : Q17 Fuel Injector
    2. Test for less than 1 V between the test points :
      • {Q17A Fuel Injector 1} Control circuit terminal 4 @ Control module harness & Ground
      • {Q17B Fuel Injector 2} Control circuit terminal 1 @ Control module harness & Ground
      • {Q17C Fuel Injector 3} Control circuit terminal 2 @ Control module harness & Ground
      • {Q17D Fuel Injector 4} Control circuit terminal 3 @ Control module harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Repair the short to voltage on the circuit :
      • {Q17A Fuel Injector 1} Control circuit terminal 8
      • {Q17B Fuel Injector 2} Control circuit terminal 5
      • {Q17C Fuel Injector 3} Control circuit terminal 6
      • {Q17D Fuel Injector 4} Control circuit terminal 7
    • Go to next step : If less than 1 V 
  6. Ignition/Vehicle - Off
  7. Disconnect the appropriate electrical connector : Q17 Fuel Injector
  8. Test for less than 2 ohms between the test points :
    • {Q17A Fuel Injector 1} Control circuit terminal 4 @ Control module harness & Control circuit terminal 1 @ Component harness
    • {Q17A Fuel Injector 1} Control circuit terminal 8 @ Control module harness & Control circuit terminal 2 @ Component harness
    • {Q17B Fuel Injector 2} Control circuit terminal 1 @ Control module harness & Control circuit terminal 1 @ Component harness
    • {Q17B Fuel Injector 2} Control circuit terminal 5 @ Control module harness & Control circuit terminal 2 @ Component harness
    • {Q17C Fuel Injector 3} Control circuit terminal 2 @ Control module harness & Control circuit terminal 1 @ Component harness
    • {Q17C Fuel Injector 3} Control circuit terminal 6 @ Control module harness & Control circuit terminal 2 @ Component harness
    • {Q17D Fuel Injector 4} Control circuit terminal 3 @ Control module harness & Control circuit terminal 1 @ Component harness
    • {Q17D Fuel Injector 4} Control circuit terminal 7 @ Control module harness & Control circuit terminal 2 @ Component harness
      • If 2 ohms or greater 

        Repair the open/high resistance in the circuit.

      • Go to next step : If less than 2 ohms 
  9. Test for infinite resistance between the test points : Control circuit terminal 1 @ Component harness & Control circuit terminal 2 @ Component harness
    • If less than infinite resistance 

      Repair the short between the circuits.

    • Go to next step : If infinite resistance 
  10. Verify a condition does not exist with the component : Q17 Fuel Injector - Refer to : Component Testing
    • If a condition exists 

      Replace the component : Q17 Fuel Injector

    • Go to next step : If no condition exists 
  11. Replace the component : K20 Engine Control Module

Test 3

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector : X2 @ K20 Engine Control Module
  3. Disconnect the appropriate electrical connector : Q17 Fuel Injector
  4. Test for infinite resistance between the test points : Control circuit terminal 1 @ Component harness & Control circuit terminal 2 @ Component harness
    • If less than infinite resistance 

      Repair the short between the circuits.

    • Go to next step : If infinite resistance 
  5. Test or replace the component : Q17 Fuel Injector
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