You may recall me writing about trying to figure out whether or not I
needed
a ballast resistor. Further, you may recall me venting about the PO
installing
a ballast resistor in series with the resistor wire in the loom, and me
wondering
why he did that.
To my Original question (do I need it or not?), Paul Hunt replied:
> If it is a 12v coil (2.5 to 3 ohms primary resistance) then you do need
> to
> run a white direct to the coil +ve. The white/light green also goes to
> the
> solenoid and carries a full 12v during cranking (not needed for a 12v
> coil)
> so don't just leave it dangling where it can come into contact with
> grounds.
Which essentially answered my question, and I went with it. My
co-worker (who
used to be a mechanic, and still plays the part when needed expressed
much doubt
in this. Actually, everybody I know that plays with cars outside this
list
expressed much doubt in this. Whatever, I know this must be right, the
coil
needs 12 volts, and a resistor isn't going to give it 12 volts, right?
Err, yeah,
but what about that alternator?
2 random comments cropped up over the last couple weeks.
1. Mallory ships a ballast resistor with their coils (or at least some
of them).
It is to be installed "in all cases". Even the 12V (which mine was)
has one.
2. A running car is not a 12V system. It is 14V.
So, with this in mind, I started playing with the voltmeter. Sure
enough, while the
car is running, the coil is getting 14V. Hmm. I install the extra
resistor that
came on the car, this time to the white wire I am running to +ve (rather
than the
resisted wire in the loom). Plug it all together, I get 12V at the
coil. Perfect.
So, the moral of the story: If you have a 12V coil, you _still_ might
want a
ballast resistor (though not the stock one of course), because that coil
getting
14V (which may be too much).
So, at least I know why the PO put this resistor on the car (see random
comment 1).
I have yet to figure out why he didn't check the voltage of the coil
wire first, but
what can I do about it anyway? :)
--
My opinions are mine, and do not reflect the views of the university.
http://www.wsu.edu/~aaronpw/
Security, like correctness, is not an add-on feature.
-- Andrew S. Tanenbaum
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