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Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 5 (Engine Controls And Fuel - 6.0L (L96) - DTC P0010 To DTC P0341) >> Diagnostic Information And Procedures >> DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308: Misfire Detected >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify the following conditions do not exist:
    • Engine - Vacuum leak
    • Exhaust System - Leaking/Missing components/Restricted - Refer to Symptoms - Engine Exhaust
    • Fuel - Contaminated/Dirty/Fill Level = Low - Refer to Alcohol/Contaminants-in-Fuel Diagnosis
    • Fuel Pressure - High/Low - Refer to Fuel System Diagnosis
    • Positive Crankcase Ventilation System - Leaking/Incorrect connection/Restricted
    • Spark Plug Boot - Carbon Tracking/Fluid intrusion/Visible Damage
    • Spark Plug - Carbon Tracking/Fouled/Visible Damage
    • Vacuum Hoses - Kinked/Leaking/Incorrect connection/Restricted
    • If a condition exists 

      Repair or replace as necessary.

    • Go to next step: If no conditions exist 
  2. Ignition/Vehicle - Off
  3. Disconnect the component: Spark Plug Wire @ Spark Plug
  4. Install the special tool: J-26792  Ignition Spark Tester @ Spark Plug Wire & Ground
  5. Engine - Running
  6. Verify there is spark at the special tool.
    NOTE: An erratic or weak spark is considered a no spark condition.
    • If there is no spark 
    1. Remove the appropriate component: Spark Plug Wire
    2. Test for 1, 850 to 2, 250 Ω between the test points: Each terminal of the component
    • Go to next step: If there is spark 
  7. Ignition/Vehicle - Off
  8. Verify the component specifications are correct: Spark Plug - Gap/Heat Range/Torque
    • If not correct 

      Repair or replace as necessary.

    • Go to next step: If correct 
  9. Swap the two components: Spark Plug - The original component that set the DTC & Another known good component from the vehicle
  10. Engine - Running
  11. Verify the scan tool parameter: Cylinder 1-8 Current Misfire Counter = Increments - At the original component location the DTC set.
    • If the parameter value does not increment 

      Replace the component: Spark Plug - The original component that set the DTC

    • Go to next step: If the parameter value increments 
  12. Perform the following procedure/test: Fuel Injector Balance - Refer to Fuel Injector Diagnosis

    Verify the procedure/test passes.

    • If the procedure/test does not pass 

      Replace the component that failed the test: Q17 Fuel Injector

    • Go to next step: If the procedure/test passes 
  13. Verify the condition does not exist: An engine mechanical condition. - Refer to Symptoms - Engine Mechanical
    • If a condition exists 

      Repair or replace as necessary.

    • Go to next step: If no condition exists 
  14. All OK.
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