Diagnostic_Process_Guide - 12

PLANNING AND EXECUTION

Developing a diagnostic game plan
To be successful today and in the future, you must understand
a vehicle's systems and components.
by Brandon Steckler, Contributing Editor

e've all heard the saying
" knowledge is power, "
but knowledge can be
quite profitable, too. A rock-solid
technician is one that has honed
their craft as being a problem-solver.
We often think of that person as one
who can " fix " anything. Although
that may be true, there is certainly
more to it than being good with your
hands. Having an understanding of
the systems and the components
vehicles are comprised of, along
with the goals of each, is what it
takes to be successful in today's
world of automotive service, repair,
and especially diagnosis. Learning
to leverage service information in
your diagnostic approach can yield
efficiency and success.
While it may seem counter-intuitive
to step back and tread slowly (especially
from a " flat-rate " perspective), separating oneself from the vehicle, creating a
game-plan, and seeing it through will
keep you focused on the facts. This, in
turn, will create efficiency without missing any steps. When I approach a vehicle,
I never do so without having a game plan.
For me, this means gathering pertinent
data about the components that make up
the system. I look to address:
* How are the components configured
to carry out a goal?
* What is that goal?
* How do we know whether the goal
was achieved/how is the system
monitored?
* What are some parameter IDs (PIDs)
that can give me easy-to-grab insight
into the system's functionality?

12 I Diagnostic Process I December 2020

These items can yield plenty of preliminary information about any problem,
on any system, in any vehicle. Think for
a moment how powerful of a statement
that is. Regardless of what is in your bay,
it's this information that will allow you
to efficiently solve the riddle. Think of
the game plan as nothing more than a
series of questions. I invest my time away
from the vehicle developing the questions
I wish to ask the vehicle. The tools I use
and the tests I perform will carry out the
questioning process. The results of those
tests are the answers I need to make the
necessary diagnostic decisions.

CALLING THE HUDDLE
I spend my initial diagnostic time understanding the preliminary information.
This key information can be found in
the service information. Many of us rely
on aftermarket sources like ALLDATA,
Mitchell 1, Identifix, MotoLogic, etc.
Some of us purchase access to OE service
information. When it comes to answering
the age-old question, " Which source of
information is the best? " , the answer is
simply all information is the best.

TROUBLESHOOTING FLOWCHARTS -
ARE THEY OF VALUE?
I recall at one point in my career being
let down by troubleshooting flowcharts.
I was confident that any issue could be
solved so long as the flowcharts were followed. To my dismay, many times I was
left with the only option to substitute a
known-good component (like a powertrain control module [PCM] ... I'm sure
we've all been down those winding roads
a few times).

I recall being discouraged by the fact
that not only was the vehicle's ailment
still present, but I had invested a lot of
time and money and was no further along
than I was hours ago. How could this have
happened? What was the missing element
that prevented me from being successful? After all, the flowcharts were written
to help me fix the vehicle by the same
people that designed the vehicle, right?
Wrong. The flowcharts are there to
help the average factory-trained technician repair a vehicle (that's under warranty) in the most financially efficient way
the majority of the time. The flowcharts
are written concerning the most likely
failures the system(s) might encounter.
They are not written concerning our wallets. This is why we may spend so much
time with disassembly/reassembly rather
than a pursuit with logic. Of course, we
realize that the engineers who design the
flowcharts aren't necessarily the same
engineers who design the systems. There
tends to be a disconnect between the two.
Over the years I've learned that there
is key information within those flowcharts that I use every day to streamline
my diagnostic approach. Reading the
steps and following them blindly is never
recommended. Understanding what each
of the steps is asking for will give you a
good idea of what the electronic control
unit (ECU) is looking for and anticipating,
as well as a logical approach. One example
is resistance specifications - keeping in
mind that voltage drop, resistance, and
current flow all relate to one another.
Knowing what the resistance specification
is calling for will allow us to anticipate
how much current flow the circuit being

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