Not sure if I posted this in the right blace, but, I am in the process of doing a 91 F-body SD Tpi conversion on my 87 Montes SS, I purchased a book on the wiring and wiring conversion, init it states that unless you are going to be using the computer to control the tcc or cruise the vss wires are not needed. Can someone tell me if this is true.

 

as far as i know with my tpi sd swap im doin now on my 87 cc carb car you do need to hook up vss aswell as park/neutral swith wire.i bought the tpi swappers guide and it says vss is very important for sd.i am using a tcc so i wired a relay off the brake trigger wire to control it since i only have one brake switch.good luck to you on your swap.mine has been a learning experience and still going.if anyone else has a 100% answer please jump in but to my knowledge you need vss even if your not using cruise control or tcc.

 

You can program the VSS out of the ECM, but it is normally used for decel fuel cutoff and a few other minor fuel trim calculations. It also activates the cooling fans below a set speed parameter, and is used to activate Highway Fuel and Spark Modes (if used) and disables the knock sensor below a set MPH. You cna live without it, but there may be some surprises if you're not aware of what it controls.

 

Thanks for all the info, Time to locate a vss.