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Home >> Chevrolet >> 2022 >> Tahoe SSV >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 8 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (1 Of 5)) >> Diagnostic Information and Procedures >> DTC P0186, P0191-P0193, P127C, or P127D >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different variant/trim than selected.
  1. Ignition - On / Vehicle - In Service Mode
  2. Verify DTC P0186 is not set and no other DTCs are set.
    • If only DTC P0186 is set 
    1. Ignition/Vehicle - Off - For greater than 8 h
    2. Ignition - On / Vehicle - In Service Mode
    3. Verify the following parameters are within 15°C (27°F) of each other:
      • Ambient Air Temperature..
      • Fuel Rail Temperature Sensor
      • Fuel Temperature Sensor
      • If not within 15°C (27°F) of each other

        {Ambient Air Temperature..} Refer to: DTC P0071-P0074

        {Fuel Rail Temperature Sensor} Refer to: Circuit/System Testing

        {Fuel Temperature Sensor} Refer to: DTC P0181-P0184 

      • Go to next step: If within 15°C (27°F) of each other
    4. Verify the scan tool parameter: Fuel Rail Pressure Sensor/Fuel Rail Pressure Sensor 2 & Fuel Rail Temperature Sensor = The value should not spike or drop out.

      Perform the action while monitoring the parameter:

      • Wiggle the harness and connector: B47B Fuel Rail Pressure Sensor
      • Wiggle the harness and connector: K20 Engine Control Module
      • If the value spikes or drops out - Repair as necessary - Wiring / Terminal (s) / Electrical Connector (s)
      • Go to next step: If the value does not spike or drop out
    5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

      Verify the DTC does not set.

      • If the DTC sets - Refer to: Circuit/System Testing
      • Go to next step: If the DTC is not set
    6. All OK.
    • Go to next step: If other DTCs are set 
    1. Ignition - On / Vehicle - In Service Mode
    2. Verify the scan tool parameter: Fuel Rail Pressure Sensor & Fuel Rail Pressure Sensor 2 = 0.2 to 4.8 V
      • If not between 0.2 and 4.8 V 

        Refer to: Circuit/System Testing

      • Go to next step: If between 0.2 and 4.8 V 
    3. Engine - Running
    4. Perform the scan tool control function: Fuel Rail Pressure - Increase & Decrease

      Verify the scan tool parameter: Fuel Rail Pressure Sensor & Fuel Rail Pressure Sensor 2 = The value should change with each command.

      • If the value does not change 

        Refer to: Circuit/System Testing

      • Go to next step: If the value changes 
    5. Verify the following parameters are within 25 MPa (3625.9 PSI) of each other:
      • Fuel Rail Pressure Sensor
      • Fuel Rail Pressure Sensor 2
      • If not within 25 MPa (3625.9 PSI) of each other - Refer to: Circuit/System Testing
      • Go to next step: If within 25 MPa (3625.9 PSI) of each other
    6. Verify the scan tool parameter: Fuel Rail Pressure Sensor/Fuel Rail Pressure Sensor 2 & Fuel Rail Temperature Sensor = The parameter value should not change

      Perform the action while monitoring the parameter:

      • Wiggle the harness and connector: B47B Fuel Rail Pressure Sensor
      • Wiggle the harness and connector: K20 Engine Control Module
      • If the parameter value changes - Repair as necessary - Wiring / Terminal (s) / Electrical Connector (s)
      • If the parameter value does not change Go to next step: 
    7. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

      Verify the DTC does not set.

      • If the DTC sets - Refer to: Circuit/System Testing
      • Go to next step: If the DTC is not set
    8. All OK.
    • Go to next step: If no DTC is set 
  3. All OK.