Diagnostics is the main thing that separates the true technicians from the parts changers. Although it is important to have the right equipment, $40,000 worth of Snap On tools does not make you a good technician. (Although if you aren't a good technician, I don't know how you earned the money to buy that much Snap On equipment.) Neither does having 30 years of experience. No matter how long you have been doing something wrong, that never makes it right. Making mistakes is something everyone will do. You need to be able to recognize your mistakes and be willing to learn from them. Please try not to make mistakes that will cause you or someone else physical harm.
A good technician is always willing and eager to learn, whether it is from someone with more or less experience should not matter. It is important to recognize your limitations. No matter what you may think, no one knows everything about everything. When you don't know an answer, don't try to "figure it out" or guess, go to a source, person or book, and get the help you need. And if you can't get the help you need immediately, don't keep working on the problem, you might make it worse.
When you are working with someone in technical service, no matter what company, there are some things to remember:
Learn the correct terminology. We have control boxes not brains. We sell jacks not legs. You have voltage, not juice or fire. (Fire is a bad thing when dealing with electrical equipment.) You push the touch panel buttons not mash them. You mash potatoes.
Listen to the tech. rep. Take notes if necessary. A portable phone can be a useful tool. Don't rely on second hand information. Talk directly to the tech. rep. If your service manage won't let you, you need a new service manager.
Give the tech. rep. all the information you can think of, including the exact type of equipment and vehicle you are working on. Don't discuss one problem for ten minutes and then come back with "by the way, it's also doing this". That may change the rep's strategy on attacking the problem. That means you just wasted the first 10 minutes of the conversation. At $100 per hour that is $16.66 you just wasted.
Do what the tech. rep. asks you to do. You called them for a reason. If you don't want to do it their way, don't waste their time. But be prepared to see a warranty claim denied.
When the rep. asks you a question, be prepared to give an exact answer. In most cases, the word "about" should not be in your answer. If you tell me there is about 12 volts, I am pretty sure you did not take an actual meter reading. It's not "about 12 volts" or "about 6 inches" or "about 5 minutes". Use the appropriate device for the situation. Give accurate information for questions that are asked. If you don't have that information, say so. Then go get the information needed.
Keep notes as you perform the diagnostics and repair. Sometimes you don't get to talk with a service rep. immediately. Then you end up guessing when you do get to talk to them. Also, when there are discrepancies in claims with labor times and charges, you have a record of what you were told and what you did.
Know the name of your phone tech rep. Not only is it good to have it for your notes but it will probably get you a quicker response when you can give the receptionist the name of the person you need. Use authorization or reference numbers when they are used.
Keep a list of information you have used during the repair. Keep track of the diagrams or manuals you have referenced. This will make if easier for the phone tech to help you. List the page and manual numbers in your notes. Staple a copy of these to the work order, especially any information you may have given the customer.
As far as actual diagnostics, there are seven steps to perform good diagnostics. If you follow these steps, rarely, if ever, will your diagnostics prove wrong.
1. Know the system. If you don't know what you are working on, you probably won't be able to fix it. If necessary, do research. Know what kind of system it is. Know how it functions, including what it should do, when it should do it and what its limitations are. Refer to owner's manuals, repair manuals and information bulletins when possible. If you don't know what kind of system it is, you can't get the correct help or even talk to someone to get the needed help. In some cases, you won't even know if the system is not working correctly.
2. Talk to the owner or operator. This step will be more valuable as you gain experience and become more knowledgeable about the systems. There is any number of questions that you may ask depending on the situation. These are just a few. How old is it? Has it ever worked properly? Has anyone else worked on it and if so, what did they do? Does it do it all the time or is it an intermittent problem? Have you had any other recent issues? If so, what were they and how were they fixed? Was it hot outside? Was it cold outside? Was it raining? Is the vehicle having any other issues; especially when the problem is electrical in nature? These all may be pertinent questions depending on the situation.
3. Operate the system. Try to operate the system in a similar situation as when the operator experiences the problem. Watch all parts of the system. The component with an issue may make it appear that a different component is faulty. You may have to drive the vehicle to duplicate the problem. Before doing a lot of meaningless diagnostics, make sure you can confirm the complaint. If you can't confirm the complaint, refer to rules 1 and 2. Maybe the operator does not understand how the system should function or what the limitations of the system are. This is an important thing to remember, "If it's not broke you can't fix it".
4. Inspect the system. Look and check for obvious problems. Is the tank full of oil? Do the batteries have a good charge? Are there any visibly loose or corroded connections? Many times, I have repaired systems simply by tightening hydraulic or electrical connections or cleaning corroded electrical connections. Sometimes I have just had to tighten a manual release on a valve or manifold. Maybe it is just a plug that was never pushed in far enough and is now not making contact. How many times have you spent an hour or two making dozens of tests only to find a loose wire on the motor or some equally simple problem? Don't be afraid to give hydraulic or electrical connections a gentle tug. (Try not to pretend you are Hercules.) If it comes apart, that is more than likely the problem anyway.
WARNING: MAKE SURE THE VEHICLE IS SECURELY SUPPORTED SO IT CANNOT DROP OR MOVE BEFORE CHECKING CONNECTIONS. PULLING ANY TYPE OF CONNECTION LOOSE COULD CAUSE THE VEHICLE TO DROP OR MOVE CAUSING INJURY OR DEATH.
5. List the possible causes. Refer to wiring diagrams and schematics to obtain information about all components of the problem circuit; hydraulic, air or electrical. List all of the components of the problem circuit in the proper order. Include ALL components, even connections and pin to wire connections. Often, things like fittings, connectors, pin to pin connections and pin to wire connections are overlooked. List all of the components means just that, ALL of the components.
6. Reach a conclusion. Check and eliminate each component as a possible cause until you isolate the faulty component. Start at one end or the other of the circuit, never in the middle. Experience will also make this step easier as you gain a better intuition as to what the most common problems are. But be careful not to assume too much. This experience just allows you to check the most common things before doing a complete diagnostic check of the circuit. When necessary, do a complete "process of elimination" test. Using the process of elimination should always get you to the correct solution.
7. Test your conclusion. Change the fitting, repair the connection or replace the component, whatever the process of elimination test concluded was the problem. Operate the system and check that it functions properly. If there is still a problem, start over. Do the process of elimination again. Maybe you had to fix one problem to find the other. Maybe the component you replaced was faulty. Yes, this can happen. Don't be afraid to admit you missed something or made a mistake. Feeling that you can't make a mistake will make finding the problem even harder. Check your diagrams again and start over. If the problem appears to be fixed, test the system several more times in different situations if possible. If there are other items that operate in conjunction with the system you repaired, check them also. It's very embarrassing to have a customer return because his rooms now do not work when you have just fixed his hydraulic leveling system.
In conclusion, your performance in the service side of your company can mean the difference between a good reputation or a bad reputation. Treat all customers like you would like to be treated when you have an issue. Don't do things "just to get them out the door" because you don't think you will see them again. It only takes one mad customer to create a bad vision of your company to a lot of potential customers. "Service with a smile" is a good motto, but I know it can be hard to maintain sometimes. Remember this, when the customer came in and was mad or rude, it was not personal. He just wanted his vehicle fixed. Don't make it personal. That will just make it worse. As hard as it is, keep that smile on your face. If you let a customer drag you into an argument or shouting match, everyone will be mad and no one wins. Nothing disarms a mad customer quicker than someone that remains pleasant under verbal assault.
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Test for General Diagnostic Techniques