transmission no shifting from firts

i have a xj 90 limited and the problem is the trans dosent want to shift stay on first all the time, i search the forums and aparently is the tps sensor, i just want to see if something similar happen to any of you all

Low fluid will do that too - make sure it's full

i believe the 90, like my 89 has an inline fuse at the trans computer, its worth checking. the trans compoter is located under the glove box attatched to the knee bolster.