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igniter testing

Discussion in 'Electronic Basics' started by ECUguy, Oct 26, 2005.

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  1. ECUguy

    ECUguy Guest

    I was looking thru teggar's igniter (ignition module) test and noticed
    a contradiction in reference on this line, "The igniter... will only switch
    off when grounded, but not when Terminal 4 is floating." is
    contradicting with the service manual.

    The 90 Prelude service manual (link below) says, "If the WHT wire
    [comparable to Terminal 4] is shorted the igniter may be damaged"
    needs some explanations why a short will damage the igniter.

    Note that a 90 prelude igniter has three terminals and a ground.
    Coil/Battery/ECU and ground.

    The service manual seems to imply that a ground short may
    damage the igniter, although Hondas are known as electronic
    ground safe vehicles, such that accidental grounding of circuits
    isn't likely to be harmful. Already, the ECU grounds terminal 4
    to produce a spark so why bother. Ground or not, the question
    still stands. Should grounding terminal 4 on a standard 4
    terminal igniter (ignition module) cause damage?
  2. Just my guess - TeGGeR is right and the manual is not as right ;-)

    TeGGeR has had a lot of input that he sorted through, so I doubt he missed
    something so important. Manuals have been known to have glitches. There is
    also the possibility the warning didn't apply to a short to ground, but to
    other random places.

  3. jim beam

    jim beam Guest

    not in my experience. i tested a civic igniter unit this way last
    weekend and it worked fine. no damage that i could tell. don't know if
    there's any difference between the prelude & civic igniters, but it
    worked for me!
  4. Guest

    The Civic ECM/ECM (computer) pulls the igniter down to within the
    saturation voltage of a NPN power transistor. Less then .2V Not
    theory measured with a good 'scope during operation. I have trouble
    accepting that a short to ground would harm anything. This applies
    to the 1990-1991 civics. I suspect that other Hondas would be very

  5. TeGGeR®

    TeGGeR® Guest

    The igniter on my test page has those connections as well.
    I think all newer Honda igniters are basically the same.

    Whether that wire was actually a ground or whether it was
    something else was a subject of considerable debate
    in the Honda groups a while ago. The consensus ended up being
    that it was much more than a ground, hence my diagram.

    Adding fuel to the fire was a diagram I came across
    from the Rover Group in Britain, which built Hondas for a while
    under license. It too showed that wire as a ground.

    The thread that discussed this can be found here, for those
    who wish to peer-review:

    Since all that started, I received two private emails
    from individuals wishing to test their igniters off the car.
    I had not posted the test page at that point, so simply sent them my
    raw photos and text. They were both able to perform the test
    to determine that their igniters had indeed gone bad. One had a
    hard-on failure (sorry, Viagra won't fix it), one a hard-off.
    This leads me to believe that the diagrams and instructions
    are correct as written, so I don't think I ought to change
    the page.

    I can only surmise that Honda simplified the white wire's
    advertised function for the purposes of the manual.
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