I let my son take our 1995 Grand Cherokee to college. It has been a tremendous vehicle thus far. He called yesterday and said it would not shift out of 1st gear. The temperatures have been in the single digits and the vehicle has about 135,000 miles on it.

Any ideas?

Hey, yeah, I just had some transmission issues pop up on my 96 Grand Cherokee would struggle hard to shift out of first. We've had single digits also. Turned out that the trans coolant lines were bad, and two seals were bad. Got em fixed and it shifts fine now.

I would take a serious look at replacing the input sensor it's located on the trans and is as easy to change as anything, part is about 40bucks and takes 5 minutes to do. I bet thats the problem.