Eagle 1,
In re-reading the thread and my own input, I want to
make sure you don't think I was giving you a hard
time. If so, I apologize.
As I read your suggestion I couldn't initially see
where it would identify a problem (circuit). As I
re-read it, I now see what you where saying...
Not any specific circuit - just that one somewhere
could be a short.
So Yes, I would agree an unknown short to ground would
yield a spark - A fairly noticeable one too probably.
I had never ever heard that trick, and I too have a
few years of wrenching - just not as a full time job
though. In High School, I took 4 years of Auto Mechanics,
graduating in 1975.
Then in 1980, I got a B.S. in Electrical Engineering and
that too never became a full time day job.(Long Story)
When I picture electrical troubleshooting I tend to
get a tad overly analytical.
Connecting the negative battery cable closes any and
all active circuits on the car. Even if you've turned
off switched circuits there are still several that are
always hot like say the clock.
As soon as you close any circuit by manually making
the contact you can have a slight spark. It would
stand to reason that the greater the flow through a
specific circuit the larger the potential spark.
If you metered the connection you would have way more
info as to how much juice is getting loose. That was
where I was going.
As far as the capacitor, yes it's for noise suppression,
but any capacitor can in fact hold a charge, granted
not for very long usually. Any wire or metal that cuts
a magnetic field will induce/conduct some electron flow.
Since a car is a collection a large metal sheets
insulated by 4 rubber tires any field or fields nearby
can and do induce a slight charge. Then closing the
battery cable closes the isolated loop and the charges
equalize (a spark).
Ok, so that's the short story and maybe I'm a ding-ding,
but that's what I was thinking - not being critical
of your tried and true wisdom.
Joe R
