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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls And Fuel - 2.8L (LWN) Diesel - Diagnostic Information And Procedures (3 Of 3)) >> Diagnostic Information and Procedures >> DTC P20CB, P20CD, P20CE, P2670, or P2671 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector : Q67 Exhaust Aftertreatment Fuel Injector
  3. Ignition - On / Vehicle - In Service Mode
  4. Verify a test lamp turns On between the test points : Control circuit terminal 2 & Ground
    • If the test lamp does not turn On 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector : X2 @ K20 Engine Control Module
    3. Test for infinite resistance between the test points : Control circuit terminal 2 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step : If infinite resistance
    4. Test for less than 2 ohms between the test points : Control circuit terminal 2 @ Component harness & The other end of the circuit @ 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 test lamp turns On 
  5. Test for 2.3 to 2.7 V between the test points : Control circuit terminal 1 & Ground
    • If less than 2.3 V 
    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 1 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step : If infinite resistance
    4. Test for less than 2 ohms between the test points : Control circuit terminal 1 @ Component harness & The other end of the circuit @ 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
    • If greater than 2.7 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector : X1 @ K20 Engine Control Module
    3. Ignition/Vehicle - Off
    4. Test for less than 1 V between the test points : Control circuit terminal 1 @ 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 between 2.3 and 2.7 V 
  6. Test or replace the component : Q67 Exhaust Aftertreatment Fuel Injector
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