I have a 1989 305 motor with ECM 1227165 in a non-Chevy app, using a 1990 Corvette 700r4. need to sort out VSS. All I currently have is the ECM and the VSS on the tailshaft, will have to make a harness.
From my research, I can get a 4 out buffer and it will take the input from the tailshaft mounted 2 prong VSS and feed the correct signal to my ECM, brown wire (A10) . If this is correct, what part number buffer do I get?. I don't need speedo or any other functions, just ECM input. Thanks in advance
I have a wiring diagram I got off here a while back, I just need to feed the purple and yellow wires from the VSS into the buffer A and C, ground it, feed it key on power to connector H and feed the output to my ECM from F

I have a 3.73 rear end with 225-50-16 (24.8) tires if that info is needed

https://www.thirdgen.org/forums/atta...ox-schem-1.jpg

 

The GM part number for the 4 out buffer is 25071437. It will work for what you want to do.

However, when the rear ratio is changed need to change the gear(s) in the transmission that drives the VSS. Most of them are no longer available. So it can be better to use a Dakoda Digital SGI-5 box instead.

It allows for the pulse rate to be changed so that the ECM & speedometer have the correct pulse rate for the correct MPH.

RBob.

 

Thanks so much for quick reply. I am buying new tires for this car soon, I can go up or down a bit on tire size If I'm close to stock Vette, guess I need to see what rear gear and tire a 90 Vette has....

Edit: looks like Vettes have much taller rear end ratios. 2.59-3.07 with 25.6' tall tires

How big a deal is running the VSS off by that much? I have been driving it with no VSS for several 1000 miles and other than idle speed issues seems to run good

 

Ehh, Dakota digital box is not that much more in price, will go that route. Thanks again

 

That too is what I was thinking. And provides much greater flexibility.

RBob.

 

Got my Dakota digital box, got a Gm pigtail for my VSS sensor, only thing I'm not sure about yet is which wire is signal output to SG-5 box coming from the VSS, is it the purple or yellow wire?


Edit: More searching shows the purple wire is signal feed...