Technicians tend to malign DTCs (diagnostic trouble codes) as misleading and unreliable. Paradoxically, it’s a rare service personage who doesn’t use them early on in any driveability troubleshooting effort. Admit it: Pulling codes is an easy and fast way to launch the expedition to find that elusive trouble.
So how about those cases -- and there are many -- in which no codes are present? Where do you start? Easy -- with the basics. We can pretty well imagine you sitting there rolling your eyes and thinking, “How many times have I heard that before?” And well, you should hear it. Most authorities from service training instructors to aftermarket engineers agree that skipping the basics is the most prevalent cause of misdiagnosis and of perfectly good parts being returned as defective.
As a manager for one of the major tech hotlines tells us, “I really agree with Ford’s stated philosophy. In its manuals, it’ll say something like, ‘Caution: The following non-EEC (electronic engine control) areas may be the cause of the problem,’ and, ‘Stop! Think! Why are you checking the EEC system?’ From our experience on the hotline, the best thing to do is to go back to step one the basics.”
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