Date:         Thu, 16 Sep 2004 18:17:21 -0500
Reply-To:     Aerowolf <aerowolf@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Aerowolf <aerowolf@GMAIL.COM>
Subject:      Re: testing the ignition coil (85 1.9L)
Comments: To: "Daniel L. Katz" <katzd54@yahoo.com>
In-Reply-To:  <vanagon%2004091319275679@GERRY.VANAGON.COM>
Content-Type: text/plain; charset=US-ASCII

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