DRAC for 730 to 749 conversion

[Dan Plaskett]

Dig

I just got the $58 calibration from Tunercat.  In going over that this
afternoon I found the Road Speed Sensor Constant that you mentioned and the
toggle for the VSS.  Set the switch to magnetic and set the speed sensor
constant to 4000ppm.  Since I have a T-56 six speed I don't have to worry
about the TCC lockup.  So is there something in the code that I have to
disable to let the ECM know that I'm not controlling a Charge Air Coolant
solenoid but instead the primary cooling fan or do I just connect pin E8 to
my primary cooling fan solenoid and set the fan enable coolant temps high
and low?


----- Original Message -----
From: "Dig" <turbodig at yahoo.com>
To: <gmecm at diy-efi.org>
Sent: Monday, September 03, 2001 9:39 PM
Subject: Re: DRAC for 730 to 749 conversion


>
> > 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?
>
> Somewhat. There are some functions that use VSS
> extensively, TCC lockup being the most prominent.
>
> The $58 code will accept a hi/low magnetic input like
> the vette one you describe, but it has to be enabled.
> It also has a divisor in the code that can be reset
> for your gearing/tire selection.
>
> > 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.
>
> Yep, it's got all the fan logic already in there. We
> use it for Charge air pump control, but on the
> original
> Sunbird app it was a fan controller. The settings are
> all in there to make it control a fan like a stocker.
>
> What are you using to re-program?
>
>
> Later,
>
> Dig
>
>
>
>
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