Gawd, don't ya just love the electronics on these cars?

 

Guys, can someone tell me, are there buffer box on 1987 v6 Firebird?

can't figure out whether vss sends signal straight to ECM or through buffer box.

 

Yes sir. 87 v6 with electronic speedo. Buffer box is square and yellow. Remove molding and black underneath of passenger side dash. ( few small bolts. ) . There is a black medal peice that you pull down, have to remove I belive 1 screw/ bolt attaching. On this meddal bracket that slide upwards into the dash. 1 side of bracket holds your silver ECM or cars computer. And other side the Yellow Buffer box is attached. There is ways to test the witing or voltage going to the box. Buffer boxes don't usually die. In testing voltage to Buffer box onmine. I found a wire harness grounding behind dash on sharp peice of medal far behind steering wheel that wore through the harness and wires.

 

This means that somebody deleted my buffer box - there's notning both on ECM or under lower dash panel...

 

91 305tbi 5 spd to 92 305tpi (automatic harness used, kept tbi 5spd. . speedo quit and not working. 4.10 gears in rear. should i replace the signal box? is this whats located next to the ecm? or replace the vss in the trans first?

 

I would try the vss in the tranny first. I've had to replace mine once. From what I found when my speedo died, it's nearly impossible to get a new buffer (the yellow box next to the ecm) or if you find one its really expensive. Speedo's in these cars are very finnicky though mine comes and goes when it wants, hoping to invest in a brand new one soon but I gotta cough up almost a grand for a good one.