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Home >> Chevrolet >> 2021 >> Trailblazer RS, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 9 (Engine Controls And Fuel - 1.0L (L4B L4F L4G LIJ) Or 1.2L (L4H L4K LIF LIH) - Diagnostic Information And Procedures (1 Of 2)) >> Diagnostic Information and Procedures >> DTC P0131, P0132, P015A, P015B, P2237, P223C, P223E, P2243, P2251, or P2626 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: B52A Heated Oxygen Sensor 1
  3. Ignition - On/Vehicle - In Service Mode
  4. Test for 4.8 to 5.7 V between the test points: Low Reference circuit terminal 1 & Ground
    • If less than 4.8 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X2 @ K20 Engine Control Module
    3. Test for infinite resistance between the test points: Low 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 less than infinite resistance
    4. Test for less than 2 ohms between the test points: Low Reference circuit terminal 1 @ Component harness & Terminal 20 X2 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Test or replace the component: K20 Engine Control Module
    • Go to next step: If greater than 5.7 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X2 @ K20 Engine Control Module
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Low 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 5.7 V 
  5. Test for 4.8 to 5.7 V between the test points: Signal circuit terminal 2 & Ground
    • If less than 4.8 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X2 @ K20 Engine Control Module
    3. Test for infinite resistance between the test points: Signal circuit terminal 2 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If less than infinite resistance
    4. Test for less than 2 ohms between the test points: Signal circuit terminal 2 @ Component harness & Terminal 10 X2 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Test or replace the component: K20 Engine Control Module
    • Go to next step: If greater than 5.7 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X2 @ 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 2 @ 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 5.7 V 
  6. Test for 4.8 to 5.7 V between the test points: Signal circuit terminal 3 & Ground
    • If less than 4.8 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X2 @ 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.
      • Go to next step: If less than infinite resistance
    4. Test for less than 2 ohms between the test points: Signal circuit terminal 3 @ Component harness & Terminal 9 X 2 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Test or replace the component: K20 Engine Control Module
    • Go to next step: If greater than 5.7 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X2 @ 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.
      • If less than 1 V - Replace the component: K20 Engine Control Module
    • Go to next step: If between 4.8 and 5.7 V 
  7. Test for 4.8 to 5.7 V between the test points: Signal circuit terminal 7 & Ground
    • If less than 4.8 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X2 @ K20 Engine Control Module
    3. Test for infinite resistance between the test points: Signal circuit terminal 7 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If less than infinite resistance
    4. Test for less than 2 ohms between the test points: Signal circuit terminal 7 @ Component harness & Terminal 19 X 2 @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Test or replace the component: K20 Engine Control Module
    • Go to next step: If greater than 5.7 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X2 @ 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 7 @ 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 5.7 V 
  8. Verify none of the conditions listed below exist:
    • Engine - Coolant consumption - Refer to Loss of Coolant
    • Engine - Oil consumption
    • Engine - Vacuum leak
    • EVAP System - Saturated with fuel
    • Exhaust System - Leaking/Missing components/Restricted - Refer to Symptoms - Engine Exhaust
    • Fuel - Contaminated/Dirty/Fill Level = Low
    • Fuel Pressure - High/Low
    • Water intrusion in the following components or their wiring harnesses: B52 Heated Oxygen Sensor
    • If a condition exists 

      Repair as necessary

    • Go to next step: If no conditions exist 
  9. Test or replace the component: B52A Heated Oxygen Sensor 1
  10. Perform the scan tool configuration/reset function: HO2S Heater Resistance Learned Values Reset
  11. 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 

      Test or replace the component: K20 Engine Control Module

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