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Home >> GMC >> 2020 >> Terrain Denali, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 6 (Engine Controls And Fuel - 1.5L (LYX) - Diagnostic Information And Procedures (1 Of 2)) >> Diagnostic Information and Procedures >> DTC P0236, P0237, or P0238 >> 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 P0641, P0651, P0697, P06A3, P06D2 is not set.
    • Go to next step : If none of the DTCs are set 
  3. If you were sent here from DTC P0068, P0101, P0106, P0121, P01101 - Refer to : Circuit/System Testing.
  4. Verify the scan tool parameter : Throttle Body Idle Air Flow CompensationLess than 90%
    • Go to next step : If less than 90% 
  5. Perform the scan tool control function : Throttle Sweep - Start

    Verify the scan tool parameter : Throttle Position Sensors 1 and 2 = Agree

    • Go to next step : If the specified state 
  6. Verify the scan tool parameter : BARO Sensor = The value should be within the range listed in the table : Altitude Versus Barometric Pressure
    • Go to next step : If in the specified range 
  7. Verify the following parameter is within 3 kPa (.4 PSI) of the actual barometric pressure : MAP Sensor
    • Go to next step : If in the specified range 
  8. Engine idling.
  9. Verify the scan tool parameter : MAP Sensor = 26 to 52 kPa (3.8 to 7.5 PSI) - The value should change with accelerator pedal input.
    • Go to next step : If in the specified range and changes 
  10. Observe the scan tool parameter : MAF Sensor & Engine Speed.
  11. Increase the engine speed slowly to 3, 000 RPM and then back to idle.
  12. Verify the scan tool parameter : MAF Sensor = The value should change smoothly and gradually as the engine speed is increased and decreased.
    • If the value does not change smoothly and gradually 

      Refer to : DTC P0101 

    • Go to next step : If the value changes smoothly and gradually 
  13. Verify the following parameter is within 3 kPa (.4 PSI) of the actual barometric pressure : Boost Pressure Sensor
    • If not in the specified range 

      Refer to : Circuit/System Testing

    • Go to next step : If in the specified range 
  14. Verify the following parameters are within 20 kPa (2.9 PSI) of each other : - 1-2 Shift Time @ Wide Open Throttle
    • MAP Sensor
    • Boost Pressure Sensor
    • If not within 20 kPa (2.9 PSI) of each other 

      Refer to : Circuit/System Testing

    • Go to next step : If within 20 kPa (2.9 PSI) of each other 
  15. 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 
  16. All OK.
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