On a 1988 gta, what is the job of that little buffer box? does it buff the VSS signal going to the ECM, elec speedo or both? and how does it "buff" the signal?

 

lol. it doesn't "buff" the signal. it "buffers" the signal. sort of changes it from what's generated by the VSS to something the ECM can recognize.

 

Thanks- I'm getting somewhere. So the buffer doesn't output to the electric speedos at all? Does anybody know what translation it does between the VSS and the ECM? pulse input-> different pulse output?

 

Converts the VSS output, which is a 4-pulse sine-wave generator, into a square-wave signal the ECM can recognize.

On cable-driven speedometers, the buffer converts a light beam reflected off the spinning element inside the speedometer into a 2 pulse square-wave signal for the computer.