I have a 88 Iroc Z with a 700r4 and I have been thinking about swapping all my gauges out for new Auto meter ones, but where I got lost was the speedo, from what i've read my car has a mechanical cable driven speedo but the speedo I'm looking at getting is a 160 mph Electronic speedo, how would I go about swapping? I tried searching for an answer but all I found were swaps from electronic to mechanical.

 

From my understanding something like this http://autometer.com/cat_accessoriesdetail.aspx?vid=114 can't be used because the ecm needs to be able to get a signal from the speedo? Anyone?

 

Do you have the wiring diagram for your car? Can anyone post the wiring diagram for the instrument cluster for him? I've read some other forums on here and looked at the ECM pin identification for your car, and you have a speed sensor on the back of your gauge that sends the signal to the ECM for your speed. That signal is obviously electronic, so you'd have to figure out the pulses it needs and essentially use the signal generated from the aftermarket gauge for both the gauge and the ECM. Maybe searching some forums will tell you the pulses per minute your ECM needs for the standard cable driven speedo.

Edit: After reading more and looking at some pictures of the speed sensor for your car, I'm not sure where it's located. Can someone else verify the location? Is it in the tail housing of the trans or the back of the gauge? And does the cable drive the speedo, while the VSS sends the signal to the ECM, or does the ECM receive the signal from the VSS and transmit that to the speedo?

 

http://www.hioutput.com/tech/speedo.html

This may also help you out

 

Thanks! The link really helped!

 

I'm still curious about the answers to these questions too if anybody knows

 

Depends
Some have a speedo drive to the dash with the VSS signal generated there Search : "buffer box "
Others
https://www.thirdgen.org/forums/post...655-post8.html

have the electronic VSS unit installed in the trans with the signal going to the speedo then the ECM on early TPI cars
or the ECM first then to the speedo on 90 - 92 cars.