In most every service bay, scan tools have become essential pieces of diagnostic equipment.
Unfortunately, some tire dealers and shop owners don't understand that there's an enormous range of capabilities among them.
Some readers may think these statements are so obvious that they're trite—perhaps foregone conclusions. However, I encounter many owners and managers in my travels who think that one scan tool is pretty much like the next one. Then they're astonished when the tool won't read the data and perform tests they assumed it would.
In reality, the differences among scan tools can be enormous. The differences are so great that some diagnostic specialists own and maintain eight or nine scan tools. They do this, they say, because each scan tool excels at testing certain families of vehicles that they diagnose often.
These potentially glaring differences among scan tools are the reason I emphasized in my last two columns the wisdom of: 1) setting diagnostic priorities; and 2) making time for careful evaluations of equipment. Some comments and inquiries from colleagues prompted me to expand the discussion a bit more in this column.
First, a scan tool connects to an industry-standard diagnostic connector under the vehicle's dashboard. Equally important, remember that these connectors provide both "generic" as well as manufacturer-specific data.
At the risk of oversimplification, some scan tools read the manufacturer-specific data much more effectively than others do. The manufacturer-specific data may speed up a diagnosis simply because they're usually much more detailed and explicit than the generic data are.
The second thing to know is that some scan tools handle or "read" the OEM-type data better than other tools do. To put it another way: some scan tools read some or most of the manufacturer-specific data all the time; other scan tools read some or most of the manufacturer-specific data some of the time; but I'm not aware of any scan tool that reads all the manufacturer-specific data on every vehicle—that capability would be technicians' nirvana!
I encountered a prime example of this recently while testing Ford charging systems. During some diagnoses, it's very helpful to be able to read two pieces of OEM Ford data called GEN MON and GEN COM. GEN refers to the alternator; MON stands for monitor and COM stands for command.
I was doing homework on some Fords in a service shop that uses a popular aftermarket scan tool that boasted a seemingly enormous list of Ford-specific data parameters. But it didn't provide the dynamic duo of GEN MON and GEN COM. Instead, the darn thing showed two consecutive listings of the GEN MON parameter.
During a research trip to another shop, I used another colleague's aftermarket scan tool. This popular tool also showed the data parameter GEN MON. However, it didn't show GEN COM. Instead, it listed something I think was a variation of it or substitute for it. I have to research both of these instances to find out if the differences in parameters really are technical or semantic.
Mind you, these are just two potential discrepancies on one auto maker's (Ford) data presentation.
Coincidentally, I encountered another snafu doing charging system homework, this time on a Chevrolet. It involved something technicians usually call bidirectional control. This refers to a scan tool's ability to issue commands or prompts to an on-board computer system.
For instance, a tech may cue a computer to turn on or speed up an electric cooling fan. If the system's healthy, the cooling fan should respond to this command and begin running or else speed up on cue.
In my case, I was trying to command the alternator on a Chevy Cavalier to turn on and charge. A Cavalier is not an oddball or outrageously sophisticated car by any means. I was using a very popular aftermarket scan tool, yet the car's charging system wouldn't respond to its commands.
Luckily, I was able to borrow a slightly newer version of the same scan tool from another service shop—still no results.
Finally, I borrowed an entirely different aftermarket scan tool. Now the Cavalier's charging system responded to the commands first time, every time. I wouldn't have predicted this reaction in a million years. Fortunately, both of these instances were my own homework exercises on known-good vehicles. I didn't have an anxious car owner pacing away in the shop's customer waiting area, awaiting a diagnosis.
Later, I had the opportunity to repeat this set of tests at a shop in the Northwest—with the same results.
Unfortunately, the only way you may verify what works and doesn't work is to try a particular scan tool on specific vehicles and specific on-board systems. Realistically, you can't "preview" a scan tool on every vehicle. However, you can prepare meaningful demonstrations on examples of the highest-volume vehicles your dealership services.
You can condition and cajole your techs to keep logs of vehicles and systems that have been problematic on your existing scan tool(s). Then target these headache cars and systems during a live demonstration of new equipment.
To recap, this is why it's so valuable to establish diagnostic priorities before you begin shopping for new gear. You can't do this effectively without consulting your customer database and involving your entire service team in the research.
Be patient and stay alert. Thoughtful homework now will pay big dividends in the service department later.