Will an electric speedometer still function
properly with the computor disconnected?
This is a 91 FireBIRD 3.1v6 that will be receiving a healthy carbed v8 and pro-built
700r.If it won't, will a mechanical speedo
& cluster from a 85TA 305TPI auto swap into
the 91?

 

It should. Just don't put any v6 tranny up against a v8 unless you REALLY like working on your car .
The vss doesn't go just to the ecm, it goes to the speedo two and they are independant of each other as long as you didn't cut any wires.

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, Jon (350 TBI!)
91 Red My website

 

Sorry JPrevost, you're incorrect. The computer has everything to do with an electronic speedometer. The signal goes from the trans to the computer. Then the computer sends it to the speedometer. On a cable-driven speedo, the trans turns the speedo with the cable, then there is a sensor mounted on the back of the speedo that sends the signal to the computer. An electronic speedo wont work without the computer or some other way to control it. A cable speedo doesnt require the ECM.


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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-

 

I thought the VSS signal went to the VSS buffer then split the output seperatly to the ECM & speedo ?

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• my Formula Homepage
• Collision P/Ns & Diagrams (Nearly complete now!)

"Always do sober what you said you'd do drunk. That will teach
you to keep your mouth shut."

 

On some setups, like TBI ECMs, '84 - '86 (digital dash) Berlinettas, and pre '91 digital dash FB / TA's, the VSS buffer is external to the ECM, either near the ECM, or behind the driver's side kick panel, in a small plastic yellow or black box, with two plugs attached to it. With '91 & '92 V8 TPI & V6 MPI, the VSS buffer is located inside the ECM.

Brian, you could use your electronic speedo & VSS if you get a VSS buffer module from GM (for a '91 305 TBI) or from a junk yard.

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Tim

1992 Z28, 305 TPI 5 speed, 12.1 sec @ 114.7 mph

1984 Berlinetta 305 TPI Auto, 13.8 sec @ 99.7 mph