Scope & Scan - Service Repair

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Speaking of diagnostics

It’s time to avoid common mistakes and charge what you’re worth.
Thursday, May 29, 2014 - 07:00
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Editor’s Note: Our guest columnist this month is Pete Meier, technical editor.

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It’s been my good fortune to have worked with a lot of different technicians. The majority were competent, honest, intelligent individuals who were successful in repairing customer problems most of the time. But is most of the time good enough?

Your customer expects their car to be fixed right the first time. That’s what they paid you to do. Anything less is, at the least, an inconvenience to them when they have to return to your shop to have it done again. Customers don’t like having to come back for the same issue — as I’m sure most of you are aware of.

Before you even open the hood or raise the car, make sure you understand how the system you are going to work on functions. Time spent up front doing a little reading will save you time overall.

A few of these “comebacks” are caused by faulty parts or an honest mistake made during the repair process. But many are the result of basic flaws in the diagnostic process, made in the very beginning that doomed the repair from the start. Here are six to watch out for.

1. Getting tunnel vision. Tunnel vision occurs when you become convinced the problem lies in a particular system, even though your testing shows otherwise. One common example I see all too often is immediately faulting the ignition system when diagnosing misfire complaints. Even though the ignition system tests fine, tunnel vision sets in and new plugs, wires and even coils are replaced before someone gets the idea to test the other engine systems for issues — and usually locates the true cause of the misfire as a result.

2. Relying on general information. There are no generalities when it comes to repairing today’s cars. Every manufacturer has its own way of making things happen, and even that might be different among its various models. Always make sure you understand how the system you are diagnosing works on the particular vehicle you are repairing. For example, consider a late-model Jaguar with a charging rate of 15.3 volts. That seems high, doesn’t it? How many of you said it needs an alternator? Be honest!

Actually, a rate of 15.3 volts after initial start is normal on this car. The ECM starts there and then selects one of three time limits (based on other inputs) before turning the charge rate down to 13.6 volts.

3. Not checking for related Technical Service Bulletins (TSBs). Depending on the source, it is estimated that between 30 percent and 60 percent of vehicle performance issues are the result of software programming in the various control modules. Many more are related to redesigned components. How are you going to find or repair that? You’re not.

So before you spend hours trying to find a problem you can’t, take a look at TSBs early on in your diagnostic process. Found one? Make sure you test and verify that it applies to the problem you have before pronouncing the car cured.

4. Relying on “silver bullets.” Many vehicles have pattern failures we all soon know about. But just because that fixed the last Ford (Audi, Mitsubishi, etc.), doesn’t mean it will fix the one in your bay today — even if it shares the same initial symptoms. Use this information as part of your diagnostic process, consider the possibility, and then test to verify that it indeed is the cause.

5. Generalizing code definitions. While it is true that many Diagnostic Trouble Codes (DTCs) have generic definitions, many techs read these code definitions and take them literally. For example, a code sets for an oxygen sensor heater fault and the tech automatically condemns the sensor — without verification first.

Diagnosing cars takes continuous study and a commitment to excellence, and those of you who do deserve to be paid for your abilities.

Manufacturers might use standard definitions, but testing methods, enabling criterion and failure limits are uniquely defined. An EGR “Low Flow” code on a Ford is not determined the same way by the ECM as the same code on a Chrysler — and both will affect how you approach your diagnosis.

It is important to always read up on the code criteria used by the particular manufacturer of the vehicle on which you are working. Knowing exactly how the code(s) set will allow you to focus your troubleshooting methods directly at the problem at hand.

6. Not sticking to the basics. Another common mistake I’ve witnessed is techs not sticking to basic testing, especially when dealing with engine performance issues. This often is the result of, or can lead to, the dreaded tunnel vision. Follow a logical approach on every diagnosis — starting with baseline tests like relative compression, fuel pressure and volume and ignition spark quality. Only believe what your testing can confirm or deny.

What are You Worth?
One topic that comes up quite a bit is “How do we charge for diag time?” This includes any sort of diagnosis that is going to take more than a simple visual inspection. Some drivability and electrical issues can become quite involved, and take a lot of time to isolate, especially if it’s your first time on that particular problem or vehicle. After all, you have a lot more homework to do. Then there are the tools you need to diagnose these problems, none of which are cheap.

Experience certainly plays a role as well. An experienced tech should be able to find the problem faster. But then, do you charge less time to the customer? A new tech might spend all day finding what turns out to be a simple fault. Do you charge the customer eight hours? In each case, how do you pay your tech? Should the experienced guy get paid less time than the new guy? Should the new guy be penalized for being new?

Most of the shops I’ve worked for in the past charged one hour at the shop rate and paid one hour flat rate. But how does that apply when the original complaint is “The MIL light is on,” and you pull half a dozen codes that may or may not be related. What if, during your diagnostic process, you determine that it is necessary to measure engine compression on a motor that requires plenum removal to access the rear bank? How do we justify the need for additional time to the customer?

It seems to me that too many customers still think of us as “grease monkeys” and don’t understand the skills it takes to repair today’s cars. They have no problem spending $20,000 or more to buy it, but heaven forbid the repair costs more than $50!

One story I heard a long time ago is applicable to this discussion. It goes something like this:

A young man is driving across the desert when his car starts running rough. There is no sign of civilization as he continues down the highway, praying the car will make it to his destination and not leave him stranded in the middle of nowhere. Several miles along, the car is still running rough, and the young man is getting worried that he may be stuck in the middle of the desert overnight. As he crests a small ridge, he sees an old shack with two gas pumps out front on the side of the highway. Thanking God for his good fortune, he prays there is a mechanic there.

He pulls up to the shack and sees an older man, rocking in his rocker and sipping lemonade. The young man gets out of the car, and says, “Excuse me, sir. Is there someone here who can help me with my car?”

The old man rises, and offers to take a look. He first listens to the engine idling, then opens the hood, looking first to the left, then to the right. “I’ll be right back,” he says, and heads off to his garage. He returns momentarily with a small hammer in hand, leans over the engine and makes a light “tap” somewhere near the firewall.

The engine immediately runs as smooth as silk.

The young man is ecstatic that the repair was so simple. He asks the older man, “How much do I owe you?”

Without batting an eye, the old man responds, “That’ll be $89.99.”

“WHAT!” exclaims the young man. “Ninety bucks for hitting it with a hammer?”

“No, son, it’s 99 cents for the hammer tap, and $89 for knowing WHERE to tap it.”

Diagnostic technicians earn their living with a lot more than just their hands, and are professionals like any other. Charge what you’re worth, and deliver what you promise. 

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