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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 P1051, P20B9, P20BA-P20BC, P248A, or P248B >> 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 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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