The most important thing about auto repair is getting the thing you wanted fixed, fixed. If you knew what was wrong with your car you probably would attempt the repair yourself. Right. I hope not. I have a saying in my shop that the customer is hardly ever right, why else would he be there? You go to a repair shop for answers to questions and the correction of symptoms. To find problems the mechanic uses anything he can. This includes fancy and costly computers, high-tech information systems, and the best tool of all, his brain and his own experience. All of this automotive puzzle can be addressed under the heading of diagnostics.
I have customer's come in all the time and say I want a DIAGNOSTIC. My first question is what do you want diagnosed? "You know. I want to know what is wrong with my car". Well could you be more specific and tell me the symptoms so I could know which system in your car you would like me to find a problem with? "All I want is a DIAGNOSTIC" What the hell is that? I must not know anything if I do not know what a DIAGNOSTIC is!!!
The word diagnose is an a verb meaning to recognize and identify by examination and observation. A diagnostic then would be the procedure by which you arrive at a diagnosis. There is something missing here. A subject is missing. If you use the automobile as the subject this would have to include all systems. This is much too broad of a description. So what I feel is the best criteria to use is a symptom. So a diagnostic is meaningless without a symptom to diagnose. Please do not use this word as a service, it is much more.
To diagnose a brake problem you would not take apart the engine. To diagnose a water leak you would not drain the oil. To diagnose a loss of power you would not check the suspension. The idea is that a direction has to be established and symptoms have to be explained by you the customer. A blanket statement like "I need a diagnostic" is like saying "I need a Physical" when you only have a problem with your foot. If you want answers in the least amount of time give the mechanic information. You have the power to be most helpful and make a real contribution by being specific and describing exactly what you want fixed.If the service writer seems to be cross examining you, it may be information he needs to aid his mechanic in the diagnosis of your vehicle. If the charges do not include repair this does not mean you are getting ripped off. Good and accurate diagnosis takes time. You have to pay for that time spent and the labor of the actual repair. Sometimes these two items overlap but you will not always be able to determine this for yourself. The price will also depend on the use of special tools and equiptment.
After you have described in detail your problems, diagnostic work usually involves leaving your vehicle for extended periods of time. Plan for it. Remember diagnostic work is not a service. You can not in advance tell exactly how long or how much time it will require to find the problem. Estimates of cost should be given in terms of time. Starting the process may have a base fee with updates by the hour as the diagnosis procedes and more tests and procedures are needed. When you sign your work order make sure it is not blank and that this base fee is clearly written. When you have difficult problems there is one hard and fast rule that you will not like and will always be true. If the vehicle does not display a symptom nobody can fix what is not broken. We term these problems as intermitant. You may want to wait for the occurance to be less sporatic before spending money and possibly wasting time. It will help to at least find out what is right with your car. When the problem returns you will have more information to pass on to the mechanic observing the problem. There is also the chance that the problem is simple and straightforward but you have to start somewhere and you are at the mercy of the mechanic. Of course, you have a good relationship built with your primary repair facillity. You do not have to be worried. Just prepared.
Drivability problems are the most difficult of automotive diagnosis. A good road test is mandatory. Good equiptment helps. Experience is critical. Great care must be given to procedures. Information is key. The mechanic of today probably spends ten percent or more of his diagnostic time reading. Flow charts have to be followed step by step. You cannot skip a step or you may mis-diagnose. You may find an unrelated problem that needs to be repaired before you can proceed to the next step. It is just the way it is. The skills required for this kind of work are not found in a school or even in a video. These skills are developed by experience, patience and the pursuit of those skills. They are rare.
If you are lucky enough to have a primary repair facility with diagnostic capabilities you will be rewarded for your patronage the first time your problem is painstakingly solved. I think the mind-set that this type of work requires, seperates the mechanic from the technician. When I hear complaints from consumers it is most often in the diagnostic area. Either they did not fix THE problem or they fixed much more than THE problem. Maybe they never explained the problem properly. I hope the problem is just communication because that is something that you can do a lot about.
To sum up diagnostic work, it will not be easy. It will require some amount of trust on your part. You will be somewhat responsible for the outcome. It will always cost something. Diagnostic work should be performed by your primary repair facility when possible. You should leave time for the diagnosis. You will always come out ahead as far as time verses actual diagnostic time. Support the truly gifted facilities with all your business.JM