I have converted my Trans Am from a manual T5 to a Pontiac Firebird 1996 T56. both trans use an electronic speedometer. How can I not get the stock speedometer to work?

 

You need to wire in a new buffer box. Do a search here there are some threads on it.

 

Dakota digital sgi-5e
https://www.summitracing.com/parts/d...SABEgKrvPD_BwE

 

Yup. Buffer box.

Gotta get from 17 pulses per rev of the drive shaft coming from the transmission, to 2 going into the speedo. Not too tough really, kinda a no-brainer actually. Those electronic adapter boxes will fix you right up.

 

You calculate pulses per rev to ppm depending on axle ratio and tire size. Tgen figure out what you need to get a 4k ppm signal. I have used the stock buffer box to get down from a converted 8k ppm. Just use the input and tgen pull vss off the 2k cruise output.

 

The 86 Firebird has the 4004 pulse per mile VSS signal at the transmission split and converted (to 2002 ppm cruise, 4004 speedometer, 2002 ECM) by a buffer box. So you only need a single converter circuit device to reduce the trans. signal to your stock buffer box. The SGI-5E works, but a simpler device will too.

 

I have an SGI5 box and I am in NJ if you want to buy it from me