I am still working out bugs on the tpi retrofit in a streetrod project and have come up with another problem (btw thanks to JP86SS for pointing me in the right direction on the 4th gear switch indicator).
The trans has a 40 tooth vss from an astro van. Originaly I had the vss wired up to the '727 ecu and it functioned, but was just 10x too high. To correct that I wired up a drac with dip switches and it works great. The indicated speed in the ecu is right on using tunerpro. In order to use the drac I had to use the optical vss input on the ecu and flip the vss option bit.
The problem is that now I no longer have a signal from the ecu to the aftermarket dolphin electronic speedo. I know that I have the option to wire the speedo directly to the drac, but i already had it connected to the ecu. and the ecu WAS sending pulses to the speedo.
The question is:
When using the optical vss input on a 730/727 is the speedometer signal output disabled?

 

Yes, by using a 2000 ppm optical signal input to the ECM you are now not using the 4000 ppm ckt that spits out the 2000 ppm and 4000 ppm from the ECM.

As you said, use the output of the DRAC for the speedo.

 

Thanks, I suspected it was something like that but wanted to be sure before opening up the wiring harness AGAIN if I didnt have to.

At least the DRAC is mounted less than 6 inches away from the speedo on this car

Thanks
Marvin