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Home >> Chevrolet >> 2024 >> Tahoe Commercial, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls And Fuel - 3.0L (Lm2) Diesel - Diagnostic Information And Procedures (5 Of 5)) >> Diagnostic Information and Procedures >> Relative Engine Compression Test >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition/Vehicle - Off
  2. Verify the following tool contains the latest software: Oscilloscope
    • If not the latest software 

      Download - Latest software

    • Go to next step: If the latest software 
  3. Apply - Parking Brake
  4. Install - CH-51450-A Oscilloscope Diagnostic Kit & CH-51450-LEAD-A Oscilloscope Basic Lead Kit
    1. Channel A Lead: Blue @Oscilloscope
    2. Channel A Lead: Blue @ B+ & Ground
    5. NOTE:

    Hover the mouse cursor over an icon button to display the button's description.

  5. Select: Channel Options - A
  6. Select: Coupling - DC
  7. Select: ConnectDetect

    Verify the following information is correctly displayed: Connected Channels = Green

    • If the information is not correctly displayed 

      Repair the poor connection & Repeat this step

    • Go to next step: If the information is correctly displayed 
  8. Setup - CH-51450-A Oscilloscope Diagnostic Kit & CH-51450-LEAD-A Oscilloscope Basic Lead Kit
    1. Select: Guided Tests
    2. Select: Charging and Starting
    3. Select: Starting
    4. Select: Cranking Voltage
  9. Disconnect the electrical connector: X160@Fuel Injector Wiring Harness
  10. Select: Running - Start Capturing
  11. Perform the following action:
    1. {Automatic Transmission}Apply & Hold - Brake Pedal

      {Manual Transmission}Apply & Hold - Clutch Pedal

    2. Engine - Cranking - For 5 - 10 s
    3. Select: Stop Capturing

      Verify the following information is correctly displayed: The waveform valleys are all even. Refer to: Oscilloscope Waveform Library

    • If the information is not correctly displayed 

      Verify the condition does not exist with the component and repair as necessary:

      NOTE:

      The following are examples of what could cause compression issues.Inspect all mechanical components for the applicable cylinder.The list is not all encompassingRefer to: Symptoms - Engine Mechanical

    • Camshaft Lobe(s) - Visible Damage/Worn
    • Exhaust ValveorIntake Valve - Stuck Open/Visible Damage
    • Exhaust Valve SeatorIntake Valve Seat - Visible Damage
    • Piston - Cracked/Visible Damage
    • Piston Ring - Seized/Visible Damage/Worn
    • Valve Lifter - Visible Damage/Worn
    • Valve Spring - Visible Damage/Worn
    • Valve Rocker Arm - Visible Damage/Worn
    • Go to next step: If the information is correctly displayed 
  12. All OK.
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