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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 P203C or P203D >> 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 : A38 Reductant Pump and Sensor Assembly
  3. Ignition - On / Vehicle - In Service Mode
  4. Test for less than 25 ohms between the test points: Low Reference circuit terminal 6 & Ground
    • If 25 ohms or greater 
    1. Disconnect the electrical connector : X2 @ K115 Reductant Control Module
    2. Test for less than 2 ohms between the test points: Low Reference circuit terminal 6 @ Component harness & Terminal 17 X2 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K115 Reductant Control Module
    • Go to next step: If less than 25 ohms 
  5. Test for 4. 8 to 5. 2 V between the test points: 5 V Reference circuit terminal 13 & Low Reference circuit terminal 6
    • If less than 4. 8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector : K115 Reductant Control Module
    3. Test for infinite resistance between the test points: 5 V Reference circuit terminal 13 @ 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: 5 V Reference circuit terminal 13 @ Component harness & Terminal 15 X2 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K115 Reductant Control Module
    • If greater than 5. 2 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector : K115 Reductant Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: 5 V Reference circuit terminal 13 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K115 Reductant Control Module
    • Go to next step: If between 4. 8 and 5. 2 V 
  6. Ignition/Vehicle - Off
  7. Disconnect the electrical connector : K115 Reductant Control Module
  8. Test for infinite resistance between the test points: Signal circuit terminal 14 @ Component harness & Ground
    • If less than infinite resistance 

      Repair the short to ground on the circuit.

    • Go to next step: If infinite resistance 
  9. Test for less than 2 ohms between the test points: Signal circuit terminal 14 @ Component harness & Terminal 16 X2 @ Control module harness
    • If 2 ohms or greater 

      Repair the open/high resistance in the circuit.

    • Go to next step: If 2 ohms or less 
  10. Ignition - On / Vehicle - In Service Mode
  11. Test for less than 1 V between the test points: Signal circuit terminal 14 @ Component harness & Ground
    • If 1 V or greater 

      Repair the short to voltage on the circuit.

    • Go to next step: If less than 1 V 
  12. Replace the component: A38 Reductant Pump and Sensor Assembly
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