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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls And Fuel - 2.7L (L3B) - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> DTC P111E or P149A-P149E >> 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 there are no DTCs set, except DTC P111E, P149A, P149D, P149E, related to the following system/component:
    • B34A Engine Coolant Temperature Sensor 1
    • B34B Engine Coolant Temperature Sensor 2
    • B34E Engine Coolant Temperature Sensor 5
    • B34F Engine Coolant Temperature Sensor 6
    • Go to next step: If a related DTC is not set 
  3. Verify there are no DTCs set related to the following component/system:
    • B9 Ambient Air Temperature Sensor
    • B36 Engine Oil Temperature Sensor
    • B65 Manifold Absolute Pressure and Intake Air Temperature Sensor
    • B203 Radiator Coolant Temperature Sensor
    • Go to next step: If a related DTC is not set 
  4. Verify the following scan tool Freeze Frame/Failure Records parameters are within 15.8°C (28°F) of each other:
    • Start-Up Engine Coolant Temperature Sensor
    • Start-Up Engine Coolant Temperature Sensor 2
    • Start-Up Engine Coolant Temperature Sensor 5
    • Start-Up Engine Coolant Temperature Sensor 6
    • If not within 15.8°C (28°F) of each other 
    1. Ignition/Vehicle - Off
      2. NOTE:

      Test the sensor that is colder or warmer than the other temperature sensor(s).

    2. Disconnect the appropriate electrical connector: B34 Engine Coolant Temperature Sensor
    3. Disconnect the appropriate electrical connector: K20 Engine Control Module
    4. Test for less than 2 ohms between the test points: Low Reference circuit terminal 2/B @ Component harness & The other end of the circuit @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • Go to next step: If less than 2 ohms
    5. Test for less than 2 ohms between the test points: Signal circuit terminal 1/A @ Component harness & The other end of the circuit @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • Go to next step: If less than 2 ohms
    6. Test or replace the component: B34 Engine Coolant Temperature Sensor
    • Go to next step: If within 15.8°C (28°F) of each other 
  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 

      Repeat the procedure starting at step 1

    • Go to next step: If the DTC is not set 
  6. All OK.
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