DRAC for 730 to 749 conversion

[Dig]

> 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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