if the light is on it depend what t case setup ya got if you have the select trak it has a awd kind of set up ya know drive on the highway type thing then it has a 4h position for off road and 4L. the part time light means ur in 4h/4L.on the command track t-case has no awd thing and the part time light only means ur in one of the 4wd positions this is how i remeber it out of my 96 owners manual so check ur owners manual and get a chiltons/haynes repair manual they are alot of help when i get a truck its one of the first things i buy hope helped some