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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 P1051, P20B9, P20BA-P20BC, P248A, or P248B >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  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 5 to 7.5 V between the test points : Control circuit terminal 9 & Ground
    • If less than 5 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector : X2 @ K115 Reductant Control Module
    3. Test for infinite resistance between the test points : Control circuit terminal 9 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step : If less than infinite resistance
    4. Test for less than 2 ohms between the test points : Control circuit terminal 9 @ Component harness & Terminal 11 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 7.5 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector : X2 @ K115 Reductant Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points : Control circuit terminal 9 @ 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 5 and 7.5 V 
  5. Connect a test lamp between the test points : Control circuit terminal 9 & Control circuit terminal 11
  6. Ignition - On / Vehicle - In Service Mode
  7. Perform the scan tool control function : Reductant Heater 1 - On and Off

    Verify the test lamp turns On and Off.

    • If the test lamp is always Off 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector : X2 @ K115 Reductant Control Module
    3. Test for infinite resistance between the test points : Control circuit terminal 11 @ 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 11 @ Component harness & Terminal 4 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 the test lamp turns On and Off 
  8. Test or replace the component : A38 Reductant Pump and Sensor Assembly
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