I'm currently converting my '90 305 TBI to a Speed Density 350 TPI. To properly wire the VSS I need to splice into wires going into the VSS buffer box. My question is where is the buffer box. I thought it was behind the passenger side dash, but I'm not so sure anymore. I pulled out a box with a yellow connector and yellow tape around the wires. The yellow connector has a side "A" and a side "B'. Both sides are then labeled 1 to 12. From what the wiring diagram says, I'm supposed to be looking for two connectors labeled "A", "B", "C", and "D". If anyone is familiar with where the buffer box is located, please help me out. Thanks.

 

It is located under the dash near the ECM on the passenger side. It will have two connectors (C1 & C2) on it, one will have five wires and one will have two wires. C1 will have pins labeled "A" & "C", "A" is a yellow wire and "C" is a purple wire, both go to the VSS. C2 will have pins labeled "A", "C", "E", "F", & "H". "A" is ground (black/white), "C" is instrument panel (brown), "E" is cruise control (red), "F" is ECM (brown), & "H" is gauge fuse on fuse block (pink/black). Hope this helps you.

 

Hey Rick,

What's the latest with that VSS Buffer and the installation of the harness?

 

hey u guys might know the answer to my problem.... i got a 88 GTA 305... my digital speedo hasnt been working... i replaced the sensor and the gear.... and now im hearing something about a vss buffer box.... if this box isnt working would that be the reassion y im not gatting a seep reading... and also how much would it be to replace if i can????

 

bufferbox on mine anyway had a yellow plastic case on it.. If you open the case.. you'll see 1 chip and some other electronics.. if the chip was ok.. then you could repair the other electronics very easily.. and cheap cheap..

 

ok... i found the buffer box it looked ok when i as looking at it, but anyway i found another buffer box and replaced it just to see wut happens. And it didnt do anything... maybe the "new"box dont work i dont know....

 

or broken wire

 

Check your gounds. Having a bad ground will cause the buffer box to not function.

 

Funny--my car doesn't even have one. I re-wired the complete car and there's none. Speedo works tho.

 

Thats probably because you have a cable driven speedo where the buffer is in the guage cluster and looks totally different than the box. But I thought they started to use the box and electric speedos on 86+ birds? Maybe it was '87+ then since yous doesn't seem to have one.

 

They had them on some models of the 86 but not all of them.

 

Sorry guys--I was wrong! I was just putting my pass side dash together and guess what I saw--the vss buffer! Duh!!
Sorry to post wrong info.

 

Yep, in 86 and 87 if the Firebird just had the dumbass lights instead of gauges, it had a cable-driven speedo. If it came with gauges, it used the electronic speedo and buffer box.