An article I wrote for an industry trade mag.

john_gMarch 27, 2010

This is an article I wrote targeted for technicians. I just thought I'd share it here too.

"Experts, Experts, Everywhere"

Is all of the Toyota stuff in the media starting to get

under your skin a bit? Seems there are experts everywhere

who know exactly what is wrong with the cars and the

engineers are simply unaware of these simple causes. Take

the professor who rigged a few jumper wires so that he could

make a connection and simulate wide open throttle and got

himself on TV for his efforts. Of course he forced wide open

throttle by doing that, he gave the PCM the same inputs that

it would get with a full throttle command from the pedal

assembly. Any first year college electronics student would

be able to do the same thing. The problem with his approach,

just like so many of the other "experts" who have chimed in

about the unintended acceleration reports is that they are

starting with an unproven assumption about a possible

vehicle condition. Then they try to create their assumption

as proof of their idea. Technicians that have attended some

of the classes that I teach know that I call this "tainted

intuition" and it usually leads to wasted time when

performing diagnostics. None of these experts are starting

from the simple initial step of confirming the reported

problem that all of us must do in order to accurately

diagnose a vehicle condition.

When I start my "How do you test a horn" lecture I make the

students call out the correct first step before we proceed.

Many will say that they check the fuse, some will check the

horn itself, others will check the power for the horn, and

or its ground circuit. I keep them firing off suggestions

until someone finally says to reach into the car and press

on the horn pad so that they verify that the customers

concern is present on the vehicle. If the horn works when

they press on the horn pad then at that moment there is

virtually nothing for them to find. However, if it does not

blow then and only then can they move onto the second step.

All of these experts getting onto the news are skipping that

all important first step and they appear to be oblivious to

the consequences of their flawed diagnostic process.

A caller into my weekly radio show claimed that his wife had

an acceleration complaint with her Camry. With all of the

other reports in the news she became afraid of the car and

traded it in. As a technician first, I asked him several

questions about the reported incidents. Unable to give me

the details that I really wanted to hear I then asked him if

I could speak to her directly. That by the way is exactly

how I would deal with a reported vehicle problem in my shop

as well, especially when I suspect that I am not receiving

the whole story from the initial contact. The following

week, his wife called into the show and here is the

description of the reported acceleration incident with her

car from the information that she gave me. It occurred two

times and both times the vehicle was at highway speed when

she suddenly noticed that the car was accelerating while she

wasn't on the throttle. Both times she had the cruise

control engaged and it had been that way for more than ten

minutes. Both times when it happened, she hit the brake

pedal and the car immediately stopped accelerating.

Now does that description sound familiar? I don't recall a

time in my career when I haven't heard similar reports from

vehicle owners including ones where as soon as the driver

released the brake pedal the car resumed accelerating. A

faulty cruise control resume/accelerate switch "can" cause

such a reported event. I stress the can in that sentence

simply because it's one of the places to look for the

concern during a reported event, and only during a genuine

event. If you do get to experience the reported issue you

can easily accurately diagnose it, otherwise you're limited

to taking the risk of the best guess and in the caller's

case that would lead to replacing the cruise control resume

switch. The fatal flaw with this choice is that the customer

never really knows for sure if the car has been fixed or not

until it acts up and proves that it wasn't.

We have probably all had situations when we were in the

process of diagnosing a customer's concern when the circuit

suddenly started working correctly and we then could not

complete the diagnostics for the car and locate the problem

until the next time that it acted up, at least I know I've

had more than my share of these incidents. We often result

to pushing and pulling on the wiring harnesses in the hopes

that we can cause the issue to return so that we get to

resume the diagnostic process. Sometimes that worked for us,

sometimes it didn't. But the one thing that we would not do

is reach down and cut a wire in a circuit which forces it

open in order to claim that is what the problem is. Yet this

is exactly how many of the experts have tried to prove their

theories on the alleged Toyota problem. For their efforts

they have gotten themselves on TV and praise in the media,

yet if we acted like that the only media attention we would

get is from the local stations consumer editor wanting to

know why we were ripping off our customers.

One thing is certain in my opinion. If there is a genuine

issue, Toyota's engineers will find it by following a good

diagnostic process. These experts the media has been

parading in front of the cameras based on their actions

aren't qualified to work unsupervised in our bays.

John G

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john_g

It turns out I'm not the only person that has this perspective.

Here is a link that might be useful: Washington Post Article

    Bookmark   March 29, 2010 at 8:24AM
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