DRAC for 730 to 749 conversion

[Dan Plaskett]

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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