Ok so long story short I dropped the t5 from my 91 formula in favor of a T-56. I picked up a Dakota Digital SGI-5C to correct my speedo. After cruising every thread I could find several times over and several days of troubleshooting I cant get things working correctly. Everyone that has posted used a purple and yellow from the buffer on the ecm, my car doesnt have that. Any thoughts on what wires I need to find. At this time I have power/ground and the two sensor wires from the T-56.

 

If your '91 is TPI the yellow & purple wires will be at the ECM. Pins B9 & B10.

If your '91 is TBI the yellow & purple wires will be at the 4-OUT BUFFER box. Which is yellow and under the dash on the passenger side.

Note that these wires are from the VSS and need to be wired to the current T56's VSS.

Out of the SGI-5 box then again depends upon which EFI system your Formula has.

RBob.

 

Yeah I think I can see it, its way up in the dash.

 

Thats a big negative. It is TBI by the way. I pulled some dash panels and was unable to find this thing. In the videos ive seen its right on the ecm?

 

I have seen the boxes in white, but those were all in Caprice's.

RBob.

 

Fantastic call. I pulled a the trim piece under the dash sleeve and there it is, white buffer box. Guess these made their way to some birds as well.

 

Which wire do I need to use as an output? All I've seen is green but I don't have that. Theres a peach colored one that seems like its in the same spot as the green would be but I cant get any speedo with it. I have the t56 sensor ran straight to the sgi-5 with the peach not responding at 3 or 5.

 

Never mind I was able to figure things out. After looking at some pins The out feeds from "C" on the harness. Sounds like this is generally green when the buffer is yellow but mine was tan or peachy. Either way I got it cleaned up, thanks for the help!