My TPS also had a vacuum "switch", which made it easy to control the vacuum modulator on a THM350 and my THM400 switch pitch trans. 25 Dec 2005 Don Sauman <donsauman at cythera.net> writes: > Chris > > I was under the impression that it was a potentiometer as in a gas > vehicle, and might have been used to control the shift points for > say a > 4L80E.