Date:         Mon, 13 Sep 2004 19:26:51 -0400
Reply-To:     "Daniel L. Katz" <katzd54@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         "Daniel L. Katz" <katzd54@YAHOO.COM>
Subject:      Re: testing the ignition coil (85 1.9L)

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

On Mon, 13 Sep 2004 09:40:54 -0500, Aerowolf <aerowolf@GMAIL.COM> wrote:

>Heya, in my continued travails of getting Morgan running again (it
>lost spark on the highway), I have found that people seem to suggest
>that there's only a few pieces that can fail, with the coil being the
>most likely.  One of my friends has suggested that putting a test
>light on the coil contacts would be a good idea, to make sure that the
>ignition control unit is doing its proper job.  (his suggestion is
>that if the light flashes while I'm cranking it, the ICU's doing its
>job, and the coil isn't.)
>
>My question is, "where would I put the test light contacts?"  There
>are three contacts on the coil, one of which is the
>high-voltage-to-the-distributor, one is two-green-wires (marked "-1"),
>and the other is three individual black and black/white wires (marked
>"15+").
>
>Assuming I'm reading this right, the 15 terminal would be where I push
>the probe, and I would connect the clip to ground?  I don't want to
>damage my ignition system, and since I'm not the best electrician on
>the planet, I'd like to make sure that my assumptions are correct.
>
>Any suggestions?  Thanks!
>
>-Kyle