How to handle が and によって in this sort of sentence?


I'll be taking a written test in a few weeks to become a part-time translator
for an automotive client; they sent me some practice documents in the
meantime.

I am having issues at the moment, since I just don't understand the context
well enough for my intuition to kick in. It's an uphill battle but I must
improve to the point where I can impress said client enough to get hired.

This is taken from a document the client sent, which features material similar
to what I would be working with:

**制御が値を下げることによって、Vehicle挙動を急変させないこと**

I made an attempt at translating it:

"The control must not suddenly change vehicle behavior due to its lowering the
value"

によって is one of my weak points when it comes to Japanese - I always get it
wrong! Also, the が is stymieing me for some reason... I am not sure whether
the "control" itself is lowering the value or not. (I think it is)

Can someone please explain how the が is functioning in relation to the
"value," and also can someone explain the proper way to translate this によって if
I have it wrong?

P.S. This is my first question on here - よろしくお願いします＾＾




> 制御が値を下げることによって、Vehicle挙動を急変させないこと

As for the "が", that particle is often used when a phrase is part of a larger
sentence (such as in this case where the term ことによって is used. (See meaning #6
in [this article of mine](http://selftaughtjapanese.com/2013/12/19/a-closer-
look-at-japanese-particles-wa-%E3%81%AF-and-ga-%E3%81%8C/))

I think in this case "制御” (control) is simply acting as the subject of 下げる. So
it is doing the lowering.

The phrase ”...ことによって” often means that "As a result of..." or simply "by".

Finally, こと can refer to a warning, I have seen this before on things written
on car parts. However, without knowing the context I cannot say how this
factors in for sure.

The other tricky part about translating this is the is the させない verb, which
can mean 'allow', but because it is in the negative I think it can be more
smoothly translated as "prevent".

So a quick attempt at a translation would be:

[code]

    The control system prevents sudden changes in vehicle behavior by lowering the value.
    
[/code]

However, without the context of what the value is and other related
information, I cannot have much confidence in this translation. If I was
translating for a job this I might look for the phrase "挙動を急変” online (and
other words) and confirm my understanding of those phrases.

I hope that helps!

UPDATE: One thing that my translation doesn't factor in directly is the ”こと"
part. I see that the original poster translated that as "must" in a
translation attempt. Depending on the context, that could be a reasonable way
to render it. Either way, I don't think the function of が or によって changes,
though.

