hey i have a 91 formula converted to a carb setup. all the computer stuff is gone and now my speedo doesn't work. How do i get it to work again? i did a search and read something about some box that converts the signal?... what do i need and where do i get it?

 

Was the harness that included the vss wiring removed?

 

When you removed the 1980's computer from your car and replaced it with 1880's technology (carb), you probably pulled out also the yellow and purple pair of wires that travels from the transmission tailshaft to the ECM (for TPI) or the yellow "VSS buffer" box (for TBI) respectively.

Diagrams here:
http://www.austinthirdgen.org/mkport...F_and_vin8.jpg
http://www.austinthirdgen.org/mkport...SS_V8_vinE.jpg

You will need to get the VSS signal from the transmission tailshaft to the yellow box (if you don't have one, you'll have to get one) and from the box to the speedometer and the cruise control module. The purpose of the yellow box is to divide the signal and also its frequency.

Another option is to downgrade the speedometer as well and go back to 1985 and put in a mechanical unit with a machanical cable attached to the tailshaft. It's not the preferred method but it's just another option.

Hope this helps.
Lou

 

i still have the wires comming from the tranny in the engine bay. i pretty much removed the ecu and engine harness everything else is still in there. so do i have this VSS box and if so where is it locatted? i'll check and see if it's there... hmm maybe it would be easier to swap to mechanical? if i get a mechanical autometer speedo what would i have to do to get it to work in my car? where do i get the mechanical transmission tail thingy?

 

ok i've been doing more searching around and i learned that from the tranny wires went to a "piggy back unit" that sat in, on or near the ecu(computer) and from that unit to the speedo. So i'm just missing the middle man essentially, the Piggy back dealy. Now is that connected to the ecu? do i need the ecu also or do i just track down this piggy back thing and hook it back up? Or if i get a autometer electronic gauge can i just hook it to the tranny or do i still need this piggy back thing?

In short, i have a electronic 700r4 and a electronic speedo what else do i need to make this work?

 

that piggy back this is a yellow box about the size of a deck of cards that is mounted next to the computer. you need the purple and blue wires that come front the trans to connect to that box, assuming you didnt have it out and loose the rest of the needed under dash wiring.