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HOMESERVICE MANUALSCHEVROLET2025EQUINOX RS, FWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 9 (ENGINE CONTROLS AND FUEL - 1.5L (LSD) - SPECIFICATIONS)SPECIFICATIONSOSCILLOSCOPE WAVEFORM LIBRARYDESCRIPTION
2025 Chevrolet Equinox RS, FWD

Oscilloscope Waveform Library: Description

2025 Chevrolet Equinox RS, FWDSECTION Description
WARNING: This page is about a different car, the 2024 GMC Terrain and 2024 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.

The figures in the tables below are reference waveforms collected from known-good vehicles and faulted vehicles. Each figure is accompanied by a description. 

Starting - Diesel Engines

Normal Abnormal
GM5700729Courtesy of GENERAL MOTORS COMPANY
  1. 8 Cylinder Engine
  2. 4 Cylinder Engine
  3. 6 Cylinder Engine
GM5700733Courtesy of GENERAL MOTORS COMPANY
  1. 3 Cylinder Engine - Low Compression
  2. Low Compression - The waveform repeats every 3 compression strokes, indicating a current and repeatable compression fault.
  3. 8 Cylinder Engine - High Starter Load
  4. Exhaust Valve = Stuck Closed - The waveform repeats every 8 compression strokes, indicating a current and repeatable compression fault. When one cylinder displays double the relative compression, this is an indication of a stuck closed exhaust valve on the companion cylinder.
NOTE:
  • An engine with little to no compression variance between cylinders will have waveform valleys that are even.
  • If the engine compression is equally low across all cylinders, the oscilloscope pattern will appear good.
  • The total amplitude (range from highest to lowest point of the waveform) is NOT an indicator of good compression.
Operating Conditions: 
  1. Fuel System - Disabled
  2. {Automatic Transmission} Apply & Hold - Brake Pedal

    {Manual Transmission} Apply & Hold - Clutch Pedal

  3. Engine - Cranking - For 5 - 10 s
Starting - Gasoline Engines

Normal Abnormal
GM5700730Courtesy of GENERAL MOTORS COMPANY
  1. 8 Cylinder Engine
  2. 6 Cylinder Engine
  3. 4 Cylinder Engine
  4. 3 Cylinder Engine
GM5700733Courtesy of GENERAL MOTORS COMPANY
  1. 3 Cylinder Engine - Low Compression
  2. Low Compression - The waveform repeats every 3 compression strokes, indicating a current and repeatable compression fault.
  3. 8 Cylinder Engine - High Starter Load
  4. Exhaust Valve = Stuck Closed - The waveform repeats every 8 compression strokes, indicating a current and repeatable compression fault. When one cylinder displays double the relative compression, this is an indication of a stuck closed exhaust valve on the companion cylinder.
NOTE:
  • An engine with little to no compression variance between cylinders will have waveform valleys that are even.
  • If the engine compression is equally low across all cylinders, the oscilloscope pattern will appear good.
  • The total amplitude (range from highest to lowest point of the waveform) is NOT an indicator of good compression.
Operating Conditions: 
  1. Fully Applied - Accelerator Pedal @ Wide Open Throttle
  2. {Automatic Transmission} Apply & Hold - Brake Pedal

    {Manual Transmission} Apply & Hold - Clutch Pedal

  3. Engine - Cranking - For 5 - 10 s
RENDER: 1.0x

NO RELATED

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.