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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 Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Verify no other DTCs are set.
    • Go to next step : If none of the DTCs are set 
  2. Verify the conditions listed in the table do not exist :
    • B65 Intake Manifold Pressure and Air Temperature Sensor - Leaking @ O-Ring - Missing / Visible Damage
    • B75C Multifunction Intake Air Sensor - Contamination of the measuring element /Cracked/Loose Clamps / Visible Damage/Water intrusion
    • B111 Turbocharger Boost Sensor
      • Leaking @ O-Ring - Missing / Visible Damage
      • Restricted - Moisture/Ice
      • Skewed
    • Q38 Throttle Body
      • Coking/Loose Clamps /Visible Damage
      • Restricted - Moisture/Ice
    • Air Cleaner Element - Dirty / Restricted
    • Catalytic Converter - Blocked / Restricted/Visible Damage
    • Charge Air Cooler
      • Leaking / Incorrect connection
      • Restricted - Moisture/Ice
    • Engine - Mechanical Condition - Refer to : Symptoms - Engine Mechanical
    • Exhaust System - Leaking /Restricted/ Visible Damage - Refer to : Symptoms - Engine Exhaust
    • Intake Air Duct - Cracked / Loose Clamps / Restricted / Visible Damage
    • Intake Manifold - Cracked / Loose Clamps / Restricted / Vacuum leak/Visible Damage
    • Linkage @ Turbocharger Wastegate Actuator - Binding or Sticking/Loose/Visible Damage
    • Positive Crankcase Ventilation System
      • Leaking @ O-Ring - Missing / Visible Damage
      • Restricted - Moisture/Ice
      • Incorrect connection /Leaking / Restricted
    • Vacuum Hoses - Kinked / Leaking / Incorrect connection / Restricted
    • Vacuum leak @ Engine - Oil Level Indicator and Tube /Oil Filler Cap
    • If a condition exists 

      Repair as necessary

    • Go to next step : If no conditions exist 
    3. NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  3. Ignition/Vehicle & All vehicle systems - Off
  4. Disconnect the electrical connector : B111 Turbocharger Boost SensorIt may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.
  5. Test for less than 5 ohms between the test points : Low Reference circuit terminal 2 & Ground
    • If 5 ohms or greater 
    1. Disconnect the electrical connector : X3 @ K20 Engine Control Module
    2. Test for less than 2 ohms between the test points : Low Reference circuit terminal 2 @ Component harness & The other end of the circuit
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component : K20 Engine Control Module
    • Go to next step : If less than 5 ohms 
  6. Ignition - On / Vehicle - In Service Mode
  7. Test for 4.8 to 5.2 V between the test points : 5 V Reference circuit terminal 1 & Ground
    • If less than 4.8 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector : X3 @ K20 Engine Control Module
    3. Test for infinite resistance between the test points : 5 V Reference circuit terminal 1 @ 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 : 5 V Reference circuit terminal 1 @ Component harness & The other end of the circuit
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component : K20 Engine Control Module
    • If greater than 5.2 V 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector : K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points : 5 V Reference circuit terminal 1 @ Component 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 
  8. Verify the scan tool parameter : Boost Pressure Sensor = Greater than 4.5 V
    • If 4.5 V or less 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector : K20 Engine Control Module
    3. Test for infinite resistance between the test points : Signal circuit terminal 3 @ Component 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
    • Go to next step : If greater than 4.5 V 
  9. Connect a 3 A fused jumper wire between the test points : Signal circuit terminal 3 & Low Reference circuit terminal 2
  10. Verify the scan tool parameter : Boost Pressure Sensor = Less than 0.2 V
    • If 0.2 V or greater 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector : K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points : Signal circuit terminal 3 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step : If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 ohms between the test points : Signal circuit terminal 3 @ Component harness & The other end of the circuit
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component : K20 Engine Control Module
    • Go to next step : If less than 0.2 V 
  11. Test or replace the component : B111 Turbocharger Boost Sensor
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