'95 Grand Cherokee can't get 1st or OD in cold weather.

Hi:

I've been having trouble with not having first gear or OD until my 1995
Jeep Grand Cherokee really warms up.

This started last year, late in the cold season but went completely away
when things warmed up. Now it's back with a vengeance. I took it to a
tranny shop and they said their was nothing obviously wrong (although
there was very minimal shavings in the fluid), and offered to tear it
apart and diagnose it for big bucks, I declined.

Now, however, I have more information to go on: I have noticed that the
"Disable OD" button on the dash is lit up whenever the problem occurs.
It can't be disabled by toggling the button, it stays lit no matter
what. Once the jeep warms up, I need to shut it down, wait for a few
seconds, then start it back up. If the light is on, I know it's not
going to work, if it goes off, I know I'm good to go.

Any ideas? Could this be a sticky sensor? Electrical problem?

Thanks for any advice.

 

Bump. Anyone?