Date: Thu, 26 Jul 2007 08:43:56 -0700
Reply-To: David Kao <dtkao0205@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Kao <dtkao0205@YAHOO.COM>
Subject: Re: Is ECU involved in getting power to fuel pump when turning
ignition switch on?
In-Reply-To: <BAY125-F212452583011E15EE90A43A0F20@phx.gbl>
Content-Type: text/plain; charset=iso-8859-1
I checked the diagram again, this time my 84's diagram which is a complete
one, I found that connection between the #15 terminal and the +12v power
from the ignition switch. I think I missed this connection when looking
at the partial diagram from the shop training manual online. There isn't
a power connection on that diagram.
So you are right that the #15 terminal is connected to +12V from the ignition
switch and the currect is flowing in from #15 and out from #1 to the ECU,
which will cutoff the current corresponding to Hall signal.
Now that the #15 has a constant $12V it changes how the relays work. The
ECU controls both relays' activation and de-activation. It is probably
controlled by the ECU's firmware, the program in the EPROM. If the fuel
pump is not pumping when it should the ECU seems to be one very likely
defective part. I would check the #15 for +12V after turning on the ignition
switch. If the pump is a new or known good working one, and it does not pump
still then swapping the relays and the ECU would be next.
David
--- Dennis Haynes <d23haynes57@HOTMAIL.COM> wrote:
> If you go with the fact that electrons are actually flowing from the
> negative terminal of the battery to the positive, then you are correct that
> pin #25 is a source. Since most folks see the positive as the source and the
> negative as the "ground", ( which it really isn't) or common, we see the
> positive and most switced connections as the source. This is called
> conventional current flow.
>
> Except for the wire from the ignition switch going through the fuse box, #15
> on the coil is feed directly off the ignition switch. There is not even a
> fuse in the way. Pin #25 completes the path to the chassis to control the
> coil as you described. This is known as a "sinking" control circuit.
>
> Dennis
>
>
> >From: David Kao <dtkao0205@YAHOO.COM>
> >Reply-To: David Kao <dtkao0205@YAHOO.COM>
> >To: vanagon@GERRY.VANAGON.COM
> >Subject: Re: Is ECU involved in getting power to fuel pump when turning
> > ignition switch on?
> >Date: Wed, 25 Jul 2007 21:11:37 -0700
> >
> >On the Bentley manual the #1 terminal is connected to the ECU's pin #25.
> >This pin is a current source controlled by the ECU. Why is it a current
> >source
> >you might ask? It is because the ignition coil's primary winding is in fact
> >an
> >inductor. Current in an inductor and voltage across a capacitor are what
> >you
> >deal with for these devices.
> >
> >In order for the secondary winding to generate high voltage the primary
> >winding
> >is first fed with a steady DC current from the ECU pin #25 into the
> >terminal #1
> >and out from #15. Upon seeing a pulse from the Hall sending unit the ECU
> >then
> >cuts off the current momentarily. The ignition coil, an inductor, will
> >react to
> >induce an EMF to counter the sudden cutoff of the current. This induced EMF
> >is
> >transformed into a high voltage on the secondary winding.
> >
> >The current flowing out of the #15 of the primary coil is used to power
> >both the
> >power supply relay and the fuel pump relay. The voltage at the #15 is
> >slightly
> >less the ther battery voltage of 14 volts. It should be arround 12 volts
> >still.
> >1 - 2 volts are dropped off due to DC resistance of the primary winding.
> >
> >If for any reason the ECU loses the pulses from the Hall sending unit, it
> >will
> >cut off the current feeding the coil. as a result #15 terminal loses the 12
> >volt
> >which then shuts off the power supply relay and the fuel pump relay. Both
> >the
> >fuel pump and all injectors are no longer powered. You will have to turn
> >the
> >ignition off then turn it back on to start all over and energize both
> >relays.
> >If you begin to crank the engine and if the ECU sees the Hall signal it
> >begins
> >to feed the coil the required current again.
> >
> >If you have a defective rotor in the ignition distributor, a defective Hall
> >sending
> >unit, a broken high voltage wire for the center terminal of the
> >distributor, a broken
> >primary or secondary winding of the ignition coil, or of course a defective
> >ECU
> >the #15 terminal will not get the 12 volt. The power supply relay and the
> >fuel pump
> >relay are de-energized. The injotors will receive no power and the fuel
> >pump will
> >not pump. If your fuel pump is not getting power and is not pumping this
> >should give
> >you some hints for troubleshooting, in addition to checking the relays.
> >
> >David
> >
> >
> >--- Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM> wrote:
> >
> > > Hi
> > > Coil terminal 15 of course is the 'ignition on' 12volts DC , terminal
> >of
> > > course.
> > > On a coil system terminal # 1 is connected to the points. ( in all
> >this
> > > wiring '1' is always associated with ground - points supply ground )
> > >
> > > Whether " Terminal #1 of the coil does get battery voltage " ....
> > > Depends on how you look at it.
> > > I'm sure there is voltage there during the process, but I wouldn't say
> >it
> > > 'gets battery voltage." I wouldn't say that at all.
> > >
> > > The purpose of ballast resistors as I understand them.....
> > > ( a small embellishment to somewhat reduce one inherit weakness of
> >points
> > > )
> > > is to reduce the voltage flowing in the points to help them last longer,
> >arc
> > > less, etc.
> > >
> > > during cranking to start, the resistor is bypassed so the points get the
> > > full 12 volts , to perk things up to help the engine fire up , during
> >'run'
> > > the points get power through the resistor, which reduces the voltage.
> > >
> > > I should hope that an ECU that is directly involved with the primary
> > > ignition circuit, as on 2.1 waterboxers and Subaru engines.....would
> >change
> > > dwell with rpm, as needed.
> > > This is an example of how extremely compromised and lame points are
> >compared
> > > to electronic ignition.
> > > It's even, I realize, very parallel to carbs/versus electronic fuel
> > > injection.
> > > The electronic system can be so precise, and optimized beautifully for
> >each
> > > different parameter, where the mechanical system, ( carb or points ) is
> >a
> > > general compromise, and subject to mechanical wear, as well.
> > > Scott
> > > wwww.turbovans.com
> > >
> > > -----Original Message-----
> > > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> >Of
> > > Dennis Haynes
> > > Sent: Wednesday, July 25, 2007 8:54 AM
> > > To: vanagon@GERRY.VANAGON.COM
> > > Subject: Re: Is ECU involved in getting power to fuel pump when turning
> > > ignition switch on?
> > >
> > > Terminal #1 of the coil does get battery voltage. The ECU switches the
> >path
> > > to the chassis in response the hall sensor. Basic ignition coil
> >operation
> > > even back to points. Points closed or ECU conducting, coil is charging,
> > > magnetic field builds. Points open or ECU opens, magnetic filed
> >collapses
> > > and high winding side of coil generates the high voltage to create a
> >spark.
> > > Back in the points day the condenser was needed to allow for the reverse
> > > current as the field collapsed and prevent the points from arching.
> >Dwell
> > > was the angle how long the points were closed. Longer is better
> >especially
> > > at higher speeds. Minimum point gap was needed though to stop arc. Some
> >cars
> > > used ballast resisters to limit current at low speed, bypassed during
> > > starting to compensate for lower battery voltage. ECU based systems will
> > > change dwell in response to speed.
> > >
> > > Dennis
> > >
> > >
> > > >From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
> > > >Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
> > > >To: vanagon@GERRY.VANAGON.COM
> > > >Subject: Re: Is ECU involved in getting power to fuel pump when turning
> > > > ignition switch on?
> > > >Date: Mon, 23 Jul 2007 21:57:31 -0700
> > > >
> > > >See SDF below -
> > > >
> > > >-----Original Message-----
> > > >From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> >Of
> > > >David Kao
> > > >Sent: Monday, July 23, 2007 9:42 PM
> > > >To: vanagon@GERRY.VANAGON.COM
> > > >Subject: Re: Is ECU involved in getting power to fuel pump when turning
> > > >ignition switch on?
> > > >
> > > >If you look at the fuel pump relay circuit you may wonder why the fuel
> > > >pump relay gets power from the #15 terminal of the ignition coil.
> > > >This terminal does not have +12V there. The #1 and #15 terminals are
> > > >the two leads of the primary winding of the ignition coil. The #1 pin
> > > >is connexted to ECU.
> > > >
> > > >I believe the ECU feeds the #1 terminal with the pulsation current,
> >which
> > > >makes the high voltage winding to generate high voltage for the spark
> > > >plugs.
> > > >This pulsation current then comes out of terminal #15 to feed to the
> >fuel
> > > >pump relay as the power source for the relay.
> > > >
> > > >If for any reason the engine stops (misfires permanently) wheile you
> >are
> > > >driving the van, the Hall sending unit will stop generating the Hall
> > > >signal.
> > > >The ECU will stop feeding the pulsation current as a result.
> >Consequently
> > > >the fuel pump relay will lose its power from the #15 terminal. As a
> >result
> > > >the relay deactivates and the fuel pump stops. This is indeed a safty
>
=== message truncated ===
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