electronic ignition

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eyes_2.4 - 20 Nov 2005 18:07 GMT

My understanding is that an electronic ignition uses a transistor
(ignition module), signal from the camshaft sensor (or pickup coil) and
ECM to pulse the negative side of the coil on and off. If this is the
case, how come so many automotive repair manuals and text books
recomend using a test light to test the negative side of the coil to
see if its pulsing? Wouldnt a test light cause some sort of damage to
the ignition system like the ignition module or ECM since its a
electronic circuit?

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aarcuda69062 - 20 Nov 2005 18:52 GMT

In article
<1132510030.867809.91410@o13g2000cwo.googlegroups.com>,

> My understanding is that an electronic ignition uses a transistor
> (ignition module), signal from the camshaft sensor (or pickup coil) and
[quoted text clipped - 4 lines]
> the ignition system like the ignition module or ECM since its a
> electronic circuit?

No.

The coil draws upwards of 6-8 amps, the test light draws around
250 milliamps or less.

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eyes_2.4 - 20 Nov 2005 19:28 GMT

So the circuit being tested needs to be drawing less amperage than the
test light is drawing in order to to cause damage?

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HLS@nospam.nix - 21 Nov 2005 01:31 GMT

What he is saying is that the extra load caused by the test light, or other
test instrument,
should be small compared with the load of the system being measured.

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