1997 jeep grand cherokee wont shift out of first gear. First it was just when it was cold now it always. Any ideas? Thanks Joe

 

Check for codes, but if I had to make a guess I would say its the trans output shaft speed sensor. If this sensor fails, the trans will not know its speed therefore it will not build gov pressure or upshift.

The sensor is cheap and easy to replace, it just screws in/out, It is located at rear of trans behind pan, and on the drivers side. I posted a pic of the sensor, and the bottom pic shows the sensor at the rear/bottom of trans ( lower right side of the pic on the trans)

 

Thanks I will check it in the am