Hi all,I'm putting in a Autometer electronic speedo,and since my car had a cable driven speedo,i'm using autometer's sender on the tranny.Does anyone know if the original vss buffer has to be used as well as the new sender.The new speedo has a out terminal which could take the signal to the ecm and cruise control,but i dont know if i still need to use the vss buffer to correct the signal out from the new sender.The car is a 85 Z28.I've done lots of searches but have'nt found the right answer.Can anybody help with this?
Thanks,Alicat.


P S,Mods,If this is in the wrong board please move.

 

The vss uses an infrared LED and a phototransistor. The vss buffer supplies the correct current to the LED and amplifies the (weak) phototransistor signal to a well defined 5V digital logic level.
If the Autometer sender has a 12V input, and an output giving a 5V logic level signal (i.e. has a built-in buffer meant to be connected direcly to an ECM) then you would not need the old vss buffer. You should then disconnect the old vss buffer so you don't get two outputs fighting each other.