kyle:

an ohm meter can be used to check the primary and seconsdary resistances,
as per bently, and the highest range can be used to check for a low grade
short to ground through the case.

a voltmeter can be used in place of the test light.

for most purposes, an inexpensive analog multi-meter is the most useful
for this type of work. the swing of the needle is a big advantage over
digital unless very precise measurments are needed.

as i mentioned, it is rare for a coil to fail, although it does happen,
and sometimers the failure is intermittent due to thermal expansion.

dan

On Thu, 16 Sep 2004 18:17:21 -0500, Aerowolf <aerowolf@GMAIL.COM> wrote:

>I just re-read this, and I realized... there's a mention of "test coil
>without a meter".
>
>What do you do to test the coil WITH a meter?  What meter?  Does it
>have to be analog or digital or something else?
>
>-Kyle
>
>
>On Mon, 13 Sep 2004 19:26:51 -0400, Daniel L. Katz <katzd54@yahoo.com>
wrote:
>> kyle:
>>
>> a bad coil is truly rare.
>>
>> first get an old spark plug and break off the side electrode to make a
>> tester. then pull off one spark plug wire at the plug and insert tester,
>> with the center electrode a few mm from a convenient ground (engine or
>> body). have an assistant crank and look for a spark. if no spark, pull
off
>> coil wire at distributor and again crank and look for a spark a few mm
to
>> ground. if no spark, and assuming coil wire is ok, then go on to the
coil.
>> your test light should have a wire with an allegator clip, which you
clip
>> to any clean unpainted ground (body or engine) to complete the circuit.
>> with an assistant cranking, test light should turn on more or less
steady
>> when touching coil (+); if not, no voltage at coil (+), which has
nothing
>> to do with the coil. assuming voltage at coil (+), light should flicker
>> when touching coil (-) while cranking; if no light, coil primary is open
>> (bad coil); if steady light, other ignition parts at fault. while
>> cranking, voltage at coil (-) normally spikes to about -300 V, which
will
>> really bite if you close the circuit with your body. if tests at coil
+/-
>> check out ok, then, since no spark, coil secondary probably shorted (bad
>> coil).
>>
>> it is hard on ignition module to make spark jump more than a few mm, or
>> worse, leave high tension side open, so either re-attach plug and coil
>> wires or ground them once you've tested for a spark.
>>
>> it is possible to have spark voltage on coil wire but no spark at plug
>> because of moisture inside cap.
>>
>> this is pretty brief, but outlines what to do to test coil without a
>> meter.
>>
>> as i said, almost all coil replacements are unnecessary - due to a
>> mistaken diagnosis, or just plain wrong guessing.
>>
>> dan