magic crystal ball

Magic crystal ball Snap-On MCB2410B

I need to explain about diagnostic charges as there is quite a lot of misunderstanding around this topic. This is going to be a long post, but I have very important considerations to say and I salute those who was able to finish this reading. Although if you don’t have time or sufficient reading skills you can jump right to Part 2

If customer would bring a car to me and say “I need to replace pigtail for connector C458, how much is it?” or “I need to replace EVAP canister vent solenoid bypass valve, what you gonna charge me for that?” there will be no need for diagnostic charge despite this would be clearly repair on some electrical system. Unfortunately customers might ask to replace a shock, change timing belt or overhaul rear diff but they never ask for something like that when it comes to electrics. They say “My heated window does not work sometimes” or “Check Engine light is on” and then it is my responsibility to find out and tell them what needs to be done.

How do I do that?

Many people now were made to believe that some kind of diagnostic computer like this diagnostic computer

needs to be connected to the car and in few minutes it’ll tell mechanic what part to replace. This is not true. Greedy shop owners and dealership managers only tell you this to justify high price of the job because “we use expensive sophisticated equipment and have to pay for that”.

To tell what is wrong with any system on any car all I need is to get my magic crystal ball from the toolbox and put my hands around it in a dark room.

I have a professional Snap-On model like the one on the header picture, but you can get a cheaper version on ebay that is almost as good for a fraction of the price of Snap-On model. It might not last as long, cheap magic crystal balls tends to wear out sooner but unless you have to fix over a hundred cars every month it would last a lifetime for you anyway (unless you break or damage it, of course). We have a special diagnostic dark room in a dealership, but even if you have a bathroom or closet without a window in your house – it’ll do to. It has to be a dark and relatively small room, I am not quite sure about the size of it but magic crystal ball does not work in a larger space like garage with closed door, or in a room with windows in a night time, or under a heavy dark blanket. For your own safety you can use a candle to provide low level of natural light, do not use any electrical powered light sources and keep magic ball away from LEDs and lasers. These days many magic crystal balls were made nonoperational by LED lights or lasers turned on in the vicinity. Because of that it is strongly recommended now to keep magic crystal ball in wooden box. Metal or plastic boxes does not provide protection from LED and laser radiation waves. Plywood, MDF and even cardboard boxes also provide some protection from LED and laser lights, although not as good as quality wooden boxes. It is pure magic, so there is no explanation why it is so.

You did not believe me for a second, did you? 🙂 I hope you didn’t…

In reality there is no magic crystal ball and no computer either that would tell technician what to do to fix a problem. Diagnostic technician needs to:

  • Verify presence of concern by testing system operation or interviewing customer
  • Have knowledge of system operation (provided by technical information sources or reverse engineering process performed on the system),
  • Use suitable equipment and tools to perform required tests and, inevitably,
  • Spend TIME to perform checks, collect data, analyze the results, make a conclusion and verify if this conclusion results in successful fix.

Compare it to this list:

  • Ask a Question
  • Do Background Research
  • Construct a Hypothesis
  • Test Your Hypothesis by Doing an Experiment
  • Analyze Your Data and Draw a Conclusion
  • Communicate Your Results

Looks similar isn’t it? Second list describes steps of scientific method. Can you see now why diagnostics is more of a science than skilled trade? And yet you still need skilled hands because diagnostics often requires a lot of remove-refit and disassembly-assembly steps. Simple check of electric circuit integrity might require to remove intake manifold (such as to check knock sensor or starter circuit on some engines)

manifold out

…pull the dash out


… drop the transmission or even pull the engine out is not something that you’ll never need to do for diagnostics.

Efficient diagnostics goes from less intrusive and time consuming tests to more intrusive ones. Logical analysis help to save time and go around labor intensive operations but sometimes there is simply no choice: we either need to do a lot of work only to check something or take a guess (I hate to take guesses despite being quite lucky at it). Cost of the parts and overall value of the vehicle also should be taken into consideration when deciding upon what path to follow in diagnostic process. For example, if access to some sensor or actuator requires lots of time and labor and part itself is not that expensive, I’d rather replace that sensor anyway after checking circuit integrity, just to eliminate possibility of sensor having a fault. Especially when dealing with intermittent problem.

Did you notice that I have not mentioned experience yet? This is because experience is much less important here. I’ve completed all Ford technical training modules just recently and guess what? There is no mention of experience there either! Whole technical training idea revolves around Symptom to System to Component to Cause (SSCC) diagnostic process. They don’t tell you “all you need is work for Ford for 30 years then you’ll be able to fix anything”. Experience plays a huge role when it comes to mechanical repairs and technician ability to perform them efficiently within very limited time frames set by manufacturer. In diagnostic process experience helps but it is not a factor deciding whether or not technician would be able to find a problem. Experience could provide technician with useful shortcuts directing him to check the most common failing components first. This could significantly reduce diagnostic time and, therefore, cost resulting in more efficient diagnostics. Sometimes almost as efficient as use of magic crystal ball ;-). Unfortunately, as we are getting more and more new models with more and more complex technologies on board – the less chances we get to rely on previous experience in order to cut diagnostic time.

As a result proportion between diagnostic time required to find a root cause of a problem and actual repair time shifts to the point where there is more time required to locate a problem than do actual repair. This diagnostic time is not “wasted” time, it is a time that was required to produce a result of diagnostic process. Result of diagnostic process is knowledge – the same as result of scientific method. We diagnosed problem and now we know what connection needs to be restored and where, or what component needs to be replaced. Or even what control unit needs to be reprogrammed in which case there is no mechanical work involved at all.

From customer’s perspective it looks like “they done nothing, they only told me what is wrong, then why I am being charged for few hours of labor?” At the same time from technician’s perspective it looks like “I had to spend few hours of my day to find a problem and now they tell me that I do not deserve to get paid because new part is too expensive and labor charges too high and customer hates us and doesn’t want to pay and goes away and leaves bad review of us – but how is this my fault?”. And from a shop owner perspective it looks like “I have to make sure that every bay and every mechanic in my shop produces sales and makes profit otherwise I want be able to pay wages, keep business running and provide profit for investors – so its either customer have to pay for the time mechanic spent working in that bay or if I can’t make customer to pay me then I am not going to pay for mechanic’s time either, he have to share my losses”

Now do you still wonder why there is so much misunderstanding and conflicts around the topic of diagnostic time charges? These are not just conflicts between shops and customers, there are plenty of conflicts and misunderstanding between technicians and people managing businesses as well. All these conflicts and misunderstanding results in poor service and excessive costs for customers caused by misdiagnosis. This industry could do much better if efforts would be coordinated and focused on goal of providing people with convenient, reliable and affordable means of personal transportation. Instead if that every party first and foremost is focused on making profit. When we have shop owners, technicians and car manufacturers all focused on their own profits then guess who is left to pay for the whole party if not the customer? Although in a bad day I feel like its me who have to pay for the whole party

I can not change the whole industry, not even mention the whole society or human race but I can do my small part to make it better.

Continue to Part 2 and thank you for reading.