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Home >> Chevrolet >> 2021 >> Blazer RS, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 9 (Engine Controls And Fuel - 2.5L (LCV) - Diagnostic Information And Procedures (1 Of 2)) >> Diagnostic Information and Procedures >> DTC P0101 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Verify the following conditions do not exist:
    • B74 Manifold Absolute Pressure Sensor - Leaking @ O-Ring - Missing / Visible Damage
    • B75C Multifunction Intake Air Sensor - Contamination of the measuring element /Cracked/Loose Clamps / Visible Damage/Water intrusion
    • Q38 Throttle Body
      • Coking/Loose Clamps /Visible Damage
      • Restricted - Moisture/Ice
    • Air Cleaner Element - Dirty / Restricted
    • Catalytic Converter - Blocked / Restricted/Visible Damage
    • 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
    • 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 as necessary

    • Go to next step: If no condition exists 
    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: B75C Multifunction Intake Air Sensor
  4. Test for less than 5 ohms between the test points: Ground circuit terminal 7 & Ground
    • If 5 ohms or greater 
    1. Disconnect the appropriate ground connection: Chassis Ground
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 7 @ Component harness & The other end of the circuit @ Chassis Ground
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 5 ohms 
  5. Ignition - On / Vehicle - In Service Mode
  6. Connect a test lamp between the test points: Ignition circuit terminal 5 & Ground
  7. Verify the test lamp turns On.
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the appropriate electrical connector: K20 Engine Control Module
    3. Test for infinite resistance between the test points: Ignition circuit terminal 5 @ 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: Ignition circuit terminal 5 @ Component harness & The other end of the circuit @ K20 Engine Control Module
      • 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 the test lamp turns On 
  8. Ignition - On / Vehicle - In Service Mode
  9. Test for 4.8 to 5.2 V between the test points: Signal circuit terminal 6 & 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: Signal circuit terminal 6 @ B75C Multifunction Intake Air Sensor & 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: Signal circuit terminal 6 @ B75C Multifunction Intake Air Sensor & The other end of the circuit @ K20 Engine Control Module
      • 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: Signal circuit terminal 6 @ B75C Multifunction Intake Air Sensor & 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 
  10. Test or replace the component: B75C Multifunction Intake Air Sensor
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