Professional Tool And Equipment News - May 2020 - 42

parts store widely varies from what a
professional technician would do when
scanning the vehicle. As you can see,
this can lead to confusion for the average
motorist who is bombarded with commercials and online ads promoting free
diagnostics.
Technicians usually connect a scan
tool when there is a problem with the
vehicle. In my shop, however, every vehicle that comes in for routine service gets a
full scan, or what is otherwise known as a
Health Check. More on the term "Health
Check" later in this article. When a technician is addressing a problem, the first
thing that I believe most do is query all
vehicle controllers (ECM, PCM, TCM,
etc.) for DTCs.
With codes in possession, what do
you do? In my personal view (and I
believe many of my colleagues would
agree), the DTC only tells part of
the story; there is a ton of diagnostic
data that should be gathered before
moving on.
OBD-II vehicles offer up a number of
additional clues through Mode$01 (live
data), Mode$02 (freeze frame), Mode$06
(diagnostic test results), Mode$09 (in-use
performance testing), and so on. These
are quite helpful in aiding the technician
who is essentially tasked with being a
"scientific diagnostic investigator," as
my colleague and friend Jorge Menchu
from Automotive Electronic Services
would say.
This is where freeze-frame can be very
helpful in surfacing clues. In one recent
case we had at my shop, a vehicle arrived
with a complaint of a flashing malfunction indicator light (MIL) and running
rough. The following DTCs were stored:
P0300, P0302, P0304, and P2198.
When the freeze-frame was reviewed
for the P2198, two indicators provided
further clues to help begin to form a
hypothesis. The glaring clue I observed
was that the bank 2 long-term and shortterm fuel trim values, together, accounted for more than a 40 percent subtraction
of the determined fuel delivery from that

PTEN

MAY 2020

bank. What we discovered was that the
B2S1 HO2S was mis-reporting a rich
condition, which resulted in the ECM
leaning out bank 2 to the point where
lean misfires began to occur.
One should have a process in place that
allows them to structurally organize this
information. My recommendation is to
store these within the work order. Many
shop management systems allow for technician notes, and some even store scan
tool reports, pictures, videos, and more.
When you're assembling your data,
think about how the data will tell the
story about the vehicle's state of health to
the customer. Doing so will help improve
your customer communications and help
everyone involved understand the vehicle
condition and needed services.
I think we can all agree that there
isn't an "easy button" (and I don't think
there ever will be) on the scan tool. This
is because the automobile is one of the
most sophisticated devices anyone will
ever use in their lifetime. Therefore,
these complicated devices actually
require skilled technicians to carry out
the appropriate test routines when performing diagnostic analysis.
I believe that one should always operate forensically prior to performing any
intrusive testing. Adherence to this discipline can save time in the long run. It's
been my experience that oftentimes the
client brings the vehicle in well after the

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The MAHLE TechPRO, a PC-based scan tool,
allows technicians to produce scan reports.

MIL first appeared, which can complicate matters.
When documenting your findings
before commencing repairs, you now
have a record of existing state of health.
This rings especially true on vehicles
possessing both persistent and intermittent DTCs. Your log is a crucial aspect
to the repair process; after addressing
the persistent DTC through repairs,
subsequent scans may result in clearing
multiple DTCs.
Having this information will provide a clear picture to the customer of
the entire repair process, as well as an
understanding that should the MIL
illuminate down the road and a previously active DTC presents itself, it is not
a returning issue, but rather a new repair
to be addressed. It's fair to assume that all
professionals want to return a vehicle to
service in the highest roadworthy condition possible, and when one is presented
with a plethora of DTCs, we can only
fix what we see and validate as broken
at the time.
When it comes to choosing a scan
tool, one needs to become highly familiar with the tool's strengths and weaknesses. Even at the OEM level, some of
their tools make it difficult to obtain the
information the technician needs quickly. Oftentimes, I find that the OBD-II

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Professional Tool And Equipment News - May 2020

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