I think the point where we were talking about making
the connection was between the PCM and solenoid #1.
There is a thing we use in HVAC called an A50 relay.
It clamps around the neutral wire on a furnace blower
motor,and when it senses current,it closes the
internal switch. It is used to turn a humidifier on
and off with the blower. If an A50 relay (or something
similar) could be clamped around a solenoid wire,and
if it worked at such low current levels (probably an
amp or less),then that would be a 100% safe way to do
this.
Steve P.
--- jon@dakota-truck.net wrote:
>
> Steve Preston <steveophonic@yahoo.com> wrote:
>
> > The diode side of an opto has basically the same
> > properties as an LED (it actually is an LED inside
> a
> > sealed case),so there really wouldn't be anything
> > gained by using extra parts. There's no real need
> for
> > isolation from the circuit. The only concern is
> > loading down the circuit,which is unlikely to
> happen.
>
>
> That's true, now that you mention it, though it
> might still be of
> some value in regards to protecting the PCM. If you
> put the
> optoisolator as close to the PCM as possible,
> anything on the LED side
> which manages to short to ground will at least not
> be seen by the PCM.
> IIRC, Bernd said that shorting that line to ground
> was likely to
> damage something. True, it doesn't help on the
> power draw side, but
> might be relatively cheap insurance to keep the PCM
> safe - who knows
> what will happen to the wires and the LED in the
> coming years? Might
> have a kid/rodent/car thief (I guess the last two
> are the same,
> sorry...) ;-) rummaging around under there at some
> point or who knows
> what.
>
> Then again, my electronic circuit experience is
> solidly in the
> amateur/hobby/sketchy area so take that for whatever
> its worth, which
> is probably not much. :-)
>
>
> Oh, something else that comes to mind is it might
> be worth taking a
> look at the MDS system in more detail - I have no
> idea how it works, I
> know earlier systems used solenoids and such, and
> now that I think of
> it, Bernd did mention a solenoid in this case. If
> they are using a
> solenoid for some reason, that might be a decent
> place to tap power
> for an LED. The power line for a solenoid, or the
> relay which
> controls the solenoid is probably going to be a heck
> of a lot less
> picky about changes than a PCM control circuit would
> be, and probably
> more forgiving in the event of a mishap as well.
> Just a thought,
> again, take it for what its worth. :-)
>
> --
> -Jon-
>
> .- Jon Steiger -- jon@dakota-truck.net or
> jon@jonsteiger.com -.
> | '96 Kolb Firefly, '96 Suzuki Intruder,
> Miscellaneous Mopars |
> `--------------------------------
> http://www.jonsteiger.com --'
>
>
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