Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Intermittent Failures Test
Intermittent concerns are the most difficult concerns to diagnose. Different techniques are required to resolve these issues without wasting repair time or replacing good components. Three procedures are used to identify an intermittent condition as soon as possible so that efforts may be directed accordingly. These are:
- Determining repeatability of DTCs at the beginning of each pinpoint test. This step helps separate repeatable conditions from intermittent conditions at the start of diagnosis and results in the elimination of performing unnecessary procedures. It also helps focus the technician's attention on the most likely issue at hand.
- Drive tests under specific conditions aimed at intermittent failures in components and wiring. Solder joints, loose connections, and weak terminations are the most common sources of intermittent operation in components and wiring. Driving raises operating temperatures of components and vibrates both the wiring and the components. It also allows the technician to perform certain maneuvers which are more likely to cause the concern to repeat and help to locate the source of the concern.
- Wiggle tests aimed at intermittent wiring concerns. This test is directly aimed at damaged loose terminals within connectors at circuit end points. It is not likely to detect an open or shorted condition of a circuit between two connectors.
For sensor failure testing, go to SENSOR FAILURE .
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When to See a Mechanic
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.
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