on the harness for switching from obd0 to obd1 there is a wire for scs i think its called says you dont have to use it but if do to wire it to a toggle. its for checking engine codes. how do i wire it to a toggle and how does it work. thanks

 

I believe it just goes to a ground. Put a toggle switch inline, whenevr the wire is grounded it works like jumping the service connector on obd1 cars and will flash any codes on the check engine light on the dash.