Answer to DRAC for 730 to 749 conversion

[Shannen Durphey]

Dan:

The 749 syty code is also used in the Turbo Sunbird.  Magnetic speed sensor
inputs are listed as BB9 and BB10 in the FSM.  Promgrammer (very slow shareware
tuner from syty site) allows changing of road speed instrument panel pulse
divisor (0x00f2), road speed sensor constant (0x00f4), and enable/disable
magnetic speed sensor (bit 6 of 0x0334).

Pin E8 is used for a cooling fan relay in this application.
Shannen

Dan Plaskett wrote:
> 
> 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 labeled 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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