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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 P0106, P0107, or P0108 >> 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. 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. Disconnect the electrical connector: B74 Manifold Absolute Pressure Sensor
  3. 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 
  4. Ignition - On / Vehicle - In Service Mode
  5. Test for 4.8 to 5.2 V between the test points: 5 V Reference circuit terminal 1 & Low Reference circuit terminal 2
    • 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 
  6. Verify the scan tool parameter: MAP 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 
  7. Connect a 3 A fused jumper wire between the test points: Signal circuit terminal 3 & Low Reference circuit terminal 2
  8. Verify the scan tool parameter: MAP 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 
  9. Verify DTC P0068, P0101, P0106, P0121, P1101 is not set.
    • If any of the DTCs are set 

      Verify the following conditions do not exist:

    • B75C Multifunction Intake Air Sensor - Contamination of the measuring element/Cracked/Loose Clamps/Visible Damage/Water intrusion
    • Q38 Throttle Body - Loose Clamps/Vacuum leak/Visible Damage
    • Air Cleaner Element - Dirty/Restricted
    • Engine - Mechanical Condition/Vacuum leak - Refer to: Symptoms - Engine Mechanical
    • Exhaust System - Leaking/Missing components/Restricted
    • Inlet @ B74 Manifold Absolute Pressure Sensor - Blocked/Leaking/Restricted/Visible Damage
    • Intake Air Duct & Intake Manifold - Cracked/Loose Clamps/Restricted/Visible Damage
    • Intake Manifold - Vacuum leak
    • O-Ring @ B74 Manifold Absolute Pressure Sensor - Leaking/Missing/Visible Damage
    • Positive Crankcase Ventilation System - Leaking/Incorrect connection/Restricted
    • Vacuum Hoses - Kinked/Leaking/Incorrect connection/Restricted
      • If a condition exists - Repair or replace as necessary
      • If no condition exists - Replace the component: B74 Manifold Absolute Pressure Sensor
    • Go to next step: If none of the DTCs are set 
  10. Test or replace the component: B74 Manifold Absolute Pressure Sensor
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