Editing Troubleshooting- a sound diagnostic approach

Identifying problems or failures in any vehicle, regardless of the system that has a problem, can be approached in the same way.  It is important to use the same basic rules and techniques to arrive at an accurate diagnosis and a successful repair.  It doesn't matter if it is an unusual noise, a leak, or a "running" problem, if you stick to the same technique you will be successful in coming to the correct conclusion.  This method can vary from person to person, but to be the most successful, it is important to stick to the same rules.  In most cases, "knowledge is key".  Everyone is familiar with this statement and in vehicle repairs it is absolutely necessary to to be well educated before you can begin to find the correct answer to a problem.  It doesn't matter how much you know, everyone, even a well seasoned service tech, will find themselves in a position where they need more knowledge about a system before they can accurately diagnose the problem and perform a reliable repair.  The most affective approach can be broken down to the following same basic steps.


1. Verify the complaint.
2. Correctly identify the affected system.
3. locate the failed component.
4. Replace the failed component.
5. Retest to prove the repair was successful.

Now these steps may look like common sense, but many are distracted as they proceed and end up "going down the wrong path" thus ariving at an incorrect conclusion and replacing the wrong part.  If you are new to repair, I recommend that you write these steps down and stick to this approach on anything you desire to fix.  Let's look at these steps one at a time.

Verify the complaint.  This is worded more at identifying what someone else is experiencing but does apply to complaints with your own vehicles as well.  Start asking questions.  Find out when the problem is most noticeable.  If it is your vehicle pay close attention to the conditions under which you can easily recreate the symptom you have noticed.  If it is someone else's vehicle be certain you have identified when and how the problem occurs so you are certain both of you are experiencing the same thing.  Do not ever begin to remove or replace anything without doing this.  Never act on an "assumption" or it will come back to bite you in the but.  Once you have narrowed down how the failure manifests, you can proceed to the next step.

Correctly identify the affected system.  Here is where your research needs to begin.  I always recommend a detailed repair manual.  Repair manuals should always be used for reference during all repairs unless you are extremely familiar with the system you are working on. If you are new to repair, find someone who knows how to explain what the most likely problem could be, and proceed with your research from there.  Even if you are a seasoned tech but don't know everything about the system you believe to be failing, detailed service manuals are important.  If you need more information find someone who is familiar with the system you are troubleshooting.  Understanding how things are designed to work will help you to distinguish a failure from normal operating  characteristics of this system.  Many repair manuals leave out information about function and design.  If you read a manufactures service manual you will find a description of what this system is designed to do.  If you understand the "operating theory" of this system, you can correctly identify if it is working properly or not.  This will help prevent you from replacing the wrong parts.  Many people are embarrassed to admit that they don't know how things work, but regardless of how long you have been doing repairs, you will always come across things you have never seen before.  It is critical to be honest with yourself and admit what you don't know.  Here's where bulletin boards and the web come in handy.  Ask as many questions as you can to learn everything you would like to know.  There are also many publications with "basic automotive theory".  Even though there are many new and innovative designs on the market today, the basic function of these systems are still the same as they were many years ago. Once you know how things are supposed to work you will be close to knowing what is wrong and approach the component that is the culprit and thus the next step.
 
Locate the failed component.  This one doesn't need much detail to explain.  Now you are looking at the correct system, what's wrong with this systems performance, and identifying which component is most likely to be creating the failure.  Now it is time to start taking bolts out and beginning your dissasembly. Here is where you will begin to understand why steps 1 & 2 are so important.  Many will begin taking things apart to explore what may have been the problem but exploratory surgery on a vehicle can be expensive and ruin your entire day.  Don't disassemble anything until you are reasonably certain that you are after the right component. Now we are on to the next step.

Replace the failed component.  There are important issues here before you do this.  First is buying a quality replacement part.  I always recommend having your replacement part on hand before you begin.  At this point you have done your best to identify what part is needed. Having to stop, clean up, and put "stuff" away then head to the parts store can leave you working into the dark hours.  I always recommend that you call around and be certain the component you believe you need is actually available to be purchased before you take anything apart.  Some times, certain components can be hard to find, especially if it is an item not manufactured as an "aftermarket" component.  Many things are only available from your local car dealer.  If it is late on a Saturday or Sunday and the vehicle is needed to get to work Monday morning, someone is going to be having a bad day! Also research to find out what else may be needed to replace the part you are after as many times there will be old or worn parts that will be removed during the repair. Hear is where your service manual comes in handy.  Read and find out what other parts you may need to "do the job right".  There are many places to by all your replacement part and I will not "bad mouth" any of the discount chains but a discount part is not the best way to go.  If you are desperate and strapped for cash you may have no choice.  However, the final step of retesting the vehicle after the repair will leave you thinking you have replaced the wrong part if the replacement is defective!  Now, after the old part is pulled, compare it to the new one to finish verifying the failure.  Now you are ready to put it back together.  Keep your manual handy as a reference during assembly.  Here is where I always giggle, as you will notice almost all manuals instructions for reassembly say, "installation is the reverse of removal".  This is however a helpful section to reference because if there is anything "special" during the assembly, you will find it there.  Once you have the reassembly process completed its time for the final step.

Retest to prove the repair was successful.  This may be more commonly called the test drive.  Reduplicate the exact same conditions under which you were able to identify the original symptoms.  If you followed this method correctly you should be successful.  

The most successful service technicians have all developed a technique similar to this one.  Do not be discouraged if you find this difficult to do as this can be complicate depending on the problem the vehicle is having.  If you feel like you have "gotten in over your head", stop and research the situation.  Someone, somewhere, has seen the same problem you are trying to identify and will know what you need to do.  "Stick to the program", and as time goes on you will begin to do this automatically.  I recommend writing down the steps, what you discovered and how.  You will discover that many vehicle system failures have the same type of symptoms and you will jump right in with your diagnosis.  Also many vehicle designs have "pattern failures" meaning the same thing goes wrong with many or all of each design.  Just continue to verify the complaint, find the right system, replace the right part,  retest and you will find great success. Have fun and good luck.