By Vince Fischelli
Many years ago, a fellow tech asked me to help him with an electrical problem that had him stumped for hours and the customer was waiting in the waiting room. For the sake of brevity, let's say he had a control box under the dash that was dead. I listened to him tell me what he had already found out and noticed the absence of concrete information about the symptoms that would tell me how to troubleshoot the problem. He told me what parts he had already replaced, the box being the first one, and other assorted parts he changed. No parts replaced had fixed the problem and now he was at the end of his rope.
I had seen this mechanical repair attitude many times before in techs that have never had any electronics troubleshooting training. If a tech has only mechanical training, he is accustomed to replacing parts that have obvious signs of failure from wear and tear. Replacing the worn out part usually restores the mechanical system to normal function. This instills a parts changing mentality in techs as a substitute for real troubleshooting in electronic systems. Troubleshooting by parts changing achieves some success in mechanical systems. Not so in electronics. If the parts changing mentality is applied to electronic systems repair, frustration and confusion are sure to follow. My friend was learning this lesson the hard way and paying the price.
I agreed to help him and first asked for the shop manual. He gave me a blank stare and said, "What do you need the book for, I thought you knew what was wrong and what to do?" (Kind of sounds like a customer doesn't he?) I patiently explained that I would not help him without having the schematic diagram of the circuit. Because he was so desperate, he went into the library area to get the manual while I got my VOM ready to take some measurements (digital meters were still too expensive in those days). I took a quick look at the disassembled front dash and realized how much time he had already wasted. Oh well, I thought, at least everything will be easy to get to since it was already laying all over the front seat and floor.
He brought me the manual and I found the page with the schematic I needed. I sensed him shuffling his feet because his impatience had gotten the best of him. I looked the schematic over and said, take these test leads and make these measurements as I call them out. The third voltage measurement told me what was wrong. I told him to resolder a bad splice in the wiring harness and began to walk away. He jumped out of the car and grabbed my arm so I couldn't leave just in case "the fix" didn't fix the problem. I assured him it would and that I had to go because I had cars I had to work on too.
When I saw him later he was smiling ear to ear telling me that "the fix" fixed the problem. He resoldered the bad slice connection and the box "came alive." Then he said something that stunned me: "Tell me how to do what you did to fix that car. I want to be able to do that too!" My mind went blank. I knew what I did, but I never spent any time talking about it. I just did it. Now I was asked for the first time point blank to explain how I did troubleshooting and the words didn't come.
Frankly, I didn't know where to start. I wondered if he know how to use a voltmeter? How to ground it? How circuits work? How to analyze a voltage reading to know what to check next? The questions came fast and furious in my mind. I stumbled through an answer but knew that I really didn't answer his question. From that moment on I began to analyze what electronic troubleshooting was all about and what steps would lead to successful troubleshooting for those interested in the subject. The search for answers continues to this day. This is the latest explanation I have come up with in a logical progression that will lead you to becoming a standout vehicle electronic systems troubleshooter. Let's call this kind of troubleshooter a VET for Vehicle Electronics Technician.
Defining a Vehicle Electronics Technician
This reference list below represents years of research into what makes someone a professional vehicle electronic systems troubleshooter, a VET, a tech that others seek for the answers to the electronic problems they cannot solve. This list isn't the end of the matter. The analysis of a VET will continue to expand as technology moves ahead. Let's see what a VET knows up to this point.
- VETs understand the operating principles of electrical and electronic circuits. A VET knows basic electrical circuit principles inside and out. A VET takes basic electrical knowledge and builds electronics knowledge on it. A VET won't bypass the electrical stuff because it's too easy or basic and considered a waste of time. A VET knows electrical theory is the basis for studying electronics. A VET knows without an electrical background, electronics can fool you into thinking you understand electronics when you really don't. Know how a VET can tell when he has a problem? If a VET troubleshoots until his store of knowledge is exhausted and the problem is still there, a VET knows he needs more training in troubleshooting. A VET never runs out of options to test, measure and evaluate readings to uncover the problem. If a VET does, he breaks out the books and studies some more until new information opens his eyes to new troubleshooting possibilities. The learning process never stops with a VET. That's why we can call him a VET - a true professional Vehicle Electronics Technician-Troubleshooter.
And yes, a VET studies Ohm's Law, as much as you might think it is not necessary. A VET knows a few well thought out Ohm's Law problems can explain in minutes what might take many hours to explain if only lecture and words are used. Any VET will tell you that it was Ohm's Law that really taught him how circuits work and what happens when the circuit goes bad. If someone doesn't say that about Ohm's Law then they never really studied Ohm's Law because once you have studied Ohm's Law you won't ever find a time you won't put it to use troubleshooting electrical and electronic systems. A VET knows that well. All VETs use Ohm's Law whether it be in cars, trucks, or heavy equipment just as electronic techs (ETs) use it in radios, TVs, VCRs, computers, etc.
- A VET understands the operation of voltmeters, ammeters and ohmmeters and their benefits and limitations in troubleshooting. A VET uses all three meters at different times in troubleshooting and never chooses a test light instead. A VET never uses the wrong type of meter for a given measurement. A VET can explain a bad reading in a circuit and if the way the meter is connected in the circuit is the reason the reading is wrong or if there is actually a problem in the circuit. A VET knows the correct way to use a meter in a given situation to avoid getting a good reading in a bad circuit and bypassing a problem completely.
A VET knows when to use an analog voltmeter or a digital voltmeter for a particular reading and what to check if the voltage reading is too low or too high. A VET knows when to do a direct current measurement or use a current clamp to check current in a circuit and what to do if a current reading is too high or too low.
A VET knows there are three types of ohmmeters and which one should be used to check a diode - which one should be used to check a coil or other resistive device. A VET knows an ohmmeter shouldn't be used to check a ground circuit and why it doesn't always work. A VET knows about the Diode Test feature failing to check diodes in certain situations and how to check a spike suppression diode while it is still connected in the circuit.
When some techs hear a class on voltmeters, ammeters and ohmmeters is coming to town they can find several reasons not to attend. A VET is one of the first to sign up because he knows he must know voltmeters, ammeters and ohmmeters inside and out. A VET is thoroughly experienced in volt-amp-ohm-meters before he gets into lab scopes. A VET knows there are no short cuts to mastering a lab scope. It takes training and a lot of practice and is always first with the lab scope on the job to learn more about wave forms.
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A VET knows how a circuit operates before beginning a troubleshooting scenario. A VET knows how to apply Ohm's Law to series and parallel circuits and knows their operating principles inside and out. A VET can tell what happens to voltage, current and resistance in any circuit when a change in a circuit parameter occurs. A VET can also tell from a bad voltage, current, resistance reading or imperfect wave form, what has happened in a circuit based on the change in the reading. A VET knows the principles of series, parallel and compound circuits inside and out.
- A VET follows a systematic troubleshooting procedure to measure voltage, current and resistance values where appropriate to determine what is wrong in a circuit. A VET follows proven troubleshooting procedures from respected technical sources. If a VET doesn't have a proven troubleshooting procedure to follow, he begins to develop one based on proven electronic system troubleshooting techniques he has learned to date and continues to develop the procedure until all contingencies are covered. A VET always follows systematic troubleshooting procedures to leave no stone un-turned.
- A VET knows how to analyze test readings provided by using test equipment in the correct way to pinpoint a problem in a circuit. If a reading is not understood, a VET takes additional readings and consults respected sources of repair information to resolve the issue so that the next time it will not be a problem. A VET is willing to invest a little more time in these endeavors than most techs simply because he knows it pays off in the future. A VET will also go to another vehicle that is operating normally to take some good readings for reference when the industry does not supply the necessary information even though it takes a little time. A VET knows how to research issues to resolve troubleshooting issues.
- A VET knows how to make the correct repair using manufacturer parts vs. aftermarket parts. A VET uses the recommended part and substitutes parts only with proven knowledge or experience (either his or another VET's) that it will work properly. A VET uses approved procedures for repairing electrical and electronic components, connectors and wiring and never uses temporary measures (quick fix connectors) for a final repair. A VET always avoids situations or inadequate repairs that could contribute to a come-back.
- A VET always verifies proper circuit operation and double checks his test equipment readings to verify correct circuit operation after a repair is completed. A VET knows readings must be normal if the circuit is properly repaired. Even when circuit performance appears normal but test equipment readings are not completely correct or normal, A VET investigates what might still be wrong.
- A VET knows to never ever assume anything, but sometimes does because he is still human. Yet, a VET recognizes human shortcomings and decides to learn as much as possible from every troubleshooting experience. A VET notes what was done correctly and what was done incorrectly, then resolves to never assume anything again. A VET researches, studies, keeps notes on what he did right and what he did wrong from every troubleshooting scenario so he can quickly solve every problem he comes across in the shortest possible time with the highest degree of proficiency at the lowest cost with the highest profit margin.
It's a tall order, but there are some who do it all, a few who do a lot of it but far too many who do little or none of it. Let's all strive to be a VET, an electronic systems troubleshooter who knows electronics troubleshooting inside and out. Go where the training is. It's an investment in your future and you just might make more money with less difficulty.
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Vince Fischelli is president of Veejer Enterprises Inc. (www.veejer.com) in Garland, Texas.
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