DRAC for 730 to 749 conversion

[Shannen Durphey]

There are several differences between the calibrations.  The sunbird cooling fan
connecton is a typical GM style fan connection.  Cooling fan paramaters begin at
0x00ad and continue through 0x00ce.  I don't know if the 4.3's are similar, but
the Sunbird uses electric cooling fans as the only means to cool the engine. 
Paramaters such as minimum fan on time and fan enable MPH may be worth looking
at.  I'd especially try to find similar paramaters in the Vette calibration for
transfer to the new file.

I've uploaded tsnbrd.bin for comparison.
ftp://ftp.diy-efi.org/incoming/tsnbrd.bin

Shannen

Dan Plaskett wrote:
> 
> 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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> 
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