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Home >> Cadillac >> 2021 >> CT4 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls And Fuel - 2.7L (L3B) - 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 the condition does not exist:
    • B65 Manifold Absolute Pressure and Intake Air Temperature Sensor - Leaking @ O-Ring - Missing / Visible Damage
    • B75 Mass Airflow Sensor - Contamination of the measuring element /Cracked/Loose Clamps / Visible Damage/Water intrusion
    • B111 Turbocharger/Supercharger Boost Pressure 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 or replace the components as necessary.

    • Go to next step: If no conditions exist 
    2. 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.

  2. Ignition/Vehicle & All vehicle systems - Off
  3. Disconnect the electrical connector: B111 Turbocharger/Supercharger Boost Pressure Sensor
  4. Test for less than 5 ohms between the test points: Low Reference circuit terminal 2 & Ground
    • If 5 ohms or greater 
    1. Disconnect the appropriate electrical connector: 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 @ Control module harness
      • 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 
  5. Ignition - On / Vehicle - In Service Mode
  6. 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 appropriate electrical connector: 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 @ Control module harness
      • 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 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: 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 
  7. Verify the scan tool parameter: Turbocharger/Supercharger Boost Pressure Sensor = Greater than 4.7 V
    • If 4.7 V or less 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate 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 4.7 V 
  8. Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 3 & Low Reference circuit terminal 2
  9. Verify the scan tool parameter: Turbocharger/Supercharger 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 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: 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 @ Control module harness
      • 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 
  10. Test or replace the component: B111 Turbocharger/Supercharger Boost Pressure Sensor
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