DRAC for 730 to 749 conversion

[Bruce]

The inputs vary from one VSS type to another.
There was a post about changing the ecm from one PPM to another
Bruce





----- Original Message -----
From: "Dan Plaskett" <dynastydaniel at home.com>
To: <gmecm at diy-efi.org>
Sent: Monday, September 03, 2001 5:39 PM
Subject: Re: DRAC for 730 to 749 conversion


> Thanks for the assist Bob and Bruce,
>
> CAC = Charge Air Cooler.  Makes sense now.  So I guess you are saying use
> the same pins for the VSS that I would have used on the 730 and in
Tunercat
> the toggle is X for magnetic and 0 for digital, so choose magnetic.  The
> SyTy parameter list in Tunercat is fairly extensive in the coolant area
but
> the document I pulled from the incoming FTP site doesn't show a pin to the
> main coolant fan solenoid.  That pin is used for the CAC.  Does the Sy/Ty
> have a primary radiator fan?  Surely it does.  Perhaps the CAC solenoid
> kicks both fans on at the same time.  Anyone have a Helm manual for the
> Sy/Ty that they could post the electrical schematics to incoming?  I'll
post
> this on the SyTy board as well.  Thanks again.
>
> One other question.  The VSS that I bought from JTR when I had them do the
> tail shaft conversion on the T-56 six speed is 4000 pulses per mile.  I
> can't seem to find it now but I thought the SyTy is looking for 2000
pulses
> per minute.  Is this going to be a problem or is the fact that the VSS has
a
> high and low input take care of this?
>
> Dan
>
> ----- Original Message -----
> From: "Bob Wooten" <r71chevy at earthlink.net>
> To: <gmecm at diy-efi.org>
> Sent: Monday, September 03, 2001 11:29 AM
> Subject: RE: DRAC for 730 to 749 conversion
>
>
> > Dan,
> >
> > I don't think that you need to do that.  the 749 has the inputs for both
> the
> > DRAC & the VSS that you are/were running.  use the VSS input & go into
the
> > prom & tell it to use the VSS & not the DRAC input.  I am using gme pro
&
> it
> > is "Mag speed sensor" & the options are Yes or NO.
> >
> > I think (as Bruce pointed out) that the CAC is the Cooling pump for the
> > air/water IC.
> >
> > Maybe TK or someone else running the SyTy code could sure this up for
us.
> I
> > am sure that the guys over @ SyTy.org would know off hand.
> >
> > BW
> >
> > -----Original Message-----
> > From: owner-gmecm at diy-efi.org [mailto:owner-gmecm at diy-efi.org]On Behalf
> > Of Dan Plaskett
> > Sent: Monday, September 03, 2001 8:54 AM
> > To: gmecm at diy-efi.org
> > Subject: DRAC for 730 to 749 conversion
> >
> >
> > In changing from 730 ECM running 1991 Corvette AXCN code to 749 ECM
> running
> > SyTy code I've run into a couple of questions.
> >
> > First, in the Corvette code there are two VSS inputs high and low that
run
> > from the VSS sensor mounted on the transmission.  The Pinout diagram for
> the
> > SyTy does not use VSS inputs but instead uses a DRAC signal on pin C6.
> > After searching and reading the archives my conclusion is that I need to
> > obtain the DRAC to get the vehicle speed information into the ECM.  I am
> > running a mechanical speedo so I am not really concerned about the VSS
> > outputs that normally drive the speedo but it seems that I still need
the
> > DRAC.  Without it the engine would have the problems associated with
> running
> > no VSS, potential for stalling, incorrect idle speed when moving, etc.
Is
> > my analysis correct?
> >
> > Second, pin E8 in the SyTy code is labled CAC control.  Is this a
cooling
> > fan control?  I can't seem to find anything else on the SyTy that looks
> like
> > the cooling fan relays on pin E8 and D12 of the Corvette code.
> >
> > TIA
> >
> > Dan Plaskett
> > 61 Corvette TPI w dual Paxton superchargers
> >
> >
>
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