Calaban007

I posted a question about the Autometer speedo the other day. I also contacted Autometer who suggested I call speedometersolutions.com. They told me they make an electric adapter that screws in where the factory cable does and it sends a signal to the computer so it thinks everything is normal. Also he said that the Autometer Speed would work correctly off of it.

My only thing is he's saying the computer uses the speedo/VSS as part of the engine management stuff. Is this true or is he just trying to sell me the adapter they make. The speedo was broken on my 86 and I've never had a minutes trouble with it as far as drivability or fuel economy. If it doesn't have anything to do with engine management I can just get the 90-92 electronic speed sender. He said the computer in the 89 uses a 2 pulse setup and the 90-92's send a 4 pulse signal. If the Autometer speedo can work with either why does it have to connect to the computer at all. What does the computer do with the vss signal? If it doesn't do anything with the engine why does it matter as long as it works?

Wadebryant

I assume your working on your 89?

In 90-92 vehicles, the computer uses the electronic vss signal to not only run the speedo but to also engauge trans lock up as well as properly regulate and adjust all of the other speed density engine management functions. What you were told is correct.

Pre-90 vehicles are mass air management controlled cars that used cable driven speedo's.

Take their advice and purchase the electronic adapter if your changing to their gauges.

Calaban007

Yeh, it's the 89, I forgot to mention it.

The reason I am asking is the speedo cable isn't turning on my IROC. Autometer makes an adapter for 65 bucks, but then I have to buy a 20 cable and possibly the sending unit mounted in the tranny. The part that Speedometersolutions.com has, mounts right to the factory sending unit and it's 95 bucks. If I buy that I may still have to buy the factory sending unit. If I just buy the electronic sending unit I could just wire it to the Autometer speedo.

What does the cable driven setup have to do with the computer on my 89 IROC' is my main question.

I mean I'll buy what I need, but I don't want to buy it if I don't need it. Like I said I can use the factory stuff and buy the 65 cable adapter, I might just do that anyway and be done with it. I don't know.