[Gmecm] 4 out buffer and 7747

[Jay Vessels]

Hi there!

'7747 wants a 2000 PPM  0-5V square wave VSS signal.

The original VSS input signal to that buffer was a 4000 PPM magnetic 
sensor, and neither input was grounded.  Not sure what the signal for 
your VSS looks like, but the more you can make it look like the GM 
signal, the better.  Do you have a 'scope?  Any pictures from it?

Jay Vessels
1982 Chevrolet S-10 Sport, 2.8V6 TBI
1984 Chevrolet S-10 Blazer Sport, 2.8V6 (TBI pending)


Brandon Austin wrote:
> I have been off list for a long time but searched/read much of the archive
> first.
> 
> I am using a 7747 to run the TBI on my '87 Toyota Land Cruiser.  I am trying
> to use the VSS in my speedo for the signal to the ECM but it is a 4 pulse.
> I tried to wire in the "4 out buffer" from a '88 Trans Am.  I know I have
> good signal in as I have tested the 4 pulse into the ECM.  I connected the
> Red/black to ign pos, the black/white to ground, the brown (2kppm?) out to
> the ECM.  For the VSS in, I have tried both the yellow to signal and purple
> to ground and the other way around.  The VSS only has signal out and is
> internally grounded.
> 
> I have also read that the buffer takes in a mag signal and puts out only
> digital.  Can the 7747 receive a digital VSS signal?  Do I just need to go
> back to the cable mounted VSS (the last one broke apart after 6 years)?
> 
> Brandon
> 
> _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/gmecm
> Main WWW page: http://www.diy-efi.org/gmecm
>