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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 21 (Engine Controls And Fuel - 4.3L (LV1) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> DTC P0641, P0651, P0697, or P06A3 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition/Vehicle - Off
    2. NOTE:

    Additional DTCs will set when disconnecting the components.

  2. Disconnect the electrical connector at one of the following components, depending on the DTC that is set :

    P0641

    • B1 A/C Refrigerant Pressure Sensor
    • B23 Camshaft Position Sensor
    • B37B Engine Oil Pressure Sensor
    • B47B Fuel Rail Pressure Sensor
    • B75C Multifunction Intake Air Sensor
    • B150 Fuel Tank Pressure Sensor

    P0651

    • B22 Brake Pedal Position Sensor
    • B26 Crankshaft Position Sensor

    P0697

    • B74 Manifold Absolute Pressure Sensor
    • B107 Accelerator Pedal Position Sensor - Sensor 2

    P06A3

    • B107 Accelerator Pedal Position Sensor - Sensor 1
    • Q38 Throttle Body
  3. Ignition - On / Vehicle - In Service Mode
  4. Verify the scan tool parameter : 5V Reference 1 - 4 Circuit Status = Malfunction - For the circuit that set the DTC.
    • If not the specified state after disconnecting a component from the circuit 

      Test or replace the component : The component that was disconnected last.

    • If the specified state and there are components connected to the circuit 

      Disconnect a component and repeat step 4.

    • Go to next step : If the specified state with all components disconnected from the circuit 
  5. Test for 4.8 to 5.2 V between the test points :

    P0641 - 5V Reference 1 Circuit

    • 5 V Reference circuit terminal 2 @ B1 A/C Refrigerant Pressure Sensor & Ground
    • 5 V Reference circuit terminal 1 @ B23 Camshaft Position Sensor & Ground
    • 5 V Reference circuit terminal 3 @ B37B Engine Oil Pressure Sensor & Ground
    • 5 V Reference circuit terminal 3 @ B47B Fuel Rail Pressure Sensor & Ground
    • 5 V Reference circuit terminal 2 @ B75C Multifunction Intake Air Sensor & Ground
    • 5 V Reference circuit terminal 3 @ B150 Fuel Tank Pressure Sensor & Ground

    P0651 - 5V Reference 2 Circuit

    • 5 V Reference circuit terminal 6 @ B22 Brake Pedal Position Sensor & Ground
    • 5 V Reference circuit terminal 3 @ B26 Crankshaft Position Sensor & Ground

    P0697 - 5V Reference 3 Circuit

    • 5 V Reference circuit terminal 1 @ B74 Manifold Absolute Pressure Sensor & Ground
    • 5 V Reference circuit terminal 1 @ B107 Accelerator Pedal Position Sensor - Sensor 2 & Ground

    P06A3 - 5V Reference 4 Circuit

    • 5 V Reference circuit terminal 2 @ B107 Accelerator Pedal Position Sensor - Sensor 1 & Ground
    • 5 V Reference circuit terminal 5 @ Q38 Throttle Body & Ground
    • If less than 4.8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate electrical connector : K20 Engine Control Module
    3. Test for infinite resistance between the test points :

      P0641

      • 5 V Reference circuit terminal 2 X3 @ Control module harness & Ground
      • 5 V Reference circuit terminal 5 X1 @ Control module harness & Ground
      • 5 V Reference circuit terminal 10 X1 @ Control module harness & Ground
      • 5 V Reference circuit terminal 18 X2 @ Control module harness & Ground
      • 5 V Reference circuit terminal 21 X1 @ Control module harness & Ground
      • 5 V Reference circuit terminal 34 X3 @ Control module harness & Ground

      P0651

      • 5 V Reference circuit terminal 10 X3 @ Control module harness & Ground
      • 5 V Reference circuit terminal 47 X1 @ Control module harness & Ground

      P0697

      • 5 V Reference circuit terminal 33 X1 @ Control module harness & Ground
      • 5 V Reference circuit terminal 44 X2 @ Control module harness & Ground

      P06A3

      • 5 V Reference circuit terminal 14 X1 @ Control module harness & Ground
      • 5 V Reference circuit terminal 34 X2 @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component : K20 Engine Control Module
    • If greater than 5.2 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate electrical connector : K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points :

      P0641

      • 5 V Reference circuit terminal 2 X3 @ Control module harness & Ground
      • 5 V Reference circuit terminal 5 X1 @ Control module harness & Ground
      • 5 V Reference circuit terminal 10 X1 @ Control module harness & Ground
      • 5 V Reference circuit terminal 18 X2 @ Control module harness & Ground
      • 5 V Reference circuit terminal 21 X1 @ Control module harness & Ground
      • 5 V Reference circuit terminal 34 X3 @ Control module harness & Ground

      P0651

      • 5 V Reference circuit terminal 10 X3 @ Control module harness & Ground
      • 5 V Reference circuit terminal 47 X1 @ Control module harness & Ground

      P0697

      • 5 V Reference circuit terminal 33 X1 @ Control module harness & Ground
      • 5 V Reference circuit terminal 44 X2 @ Control module harness & Ground

      P06A3

      • 5 V Reference circuit terminal 14 X1 @ Control module harness & Ground
      • 5 V Reference circuit terminal 34 X2 @ Control module 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 4.8 and 5.2 V 
  6. All OK.
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