1992 BMW 325 Cold start code

Transmission problem
1992 BMW 325i Two Wheel Drive Automatic 175000 miles

In temperatures below freezing, vehicle throws a Tranny trouble light which disables the automatic shifting of the vehicle (still driveable in manual shift mode without 1st gear). Once warm (2-5 minutes), turning vehicle off and removing key for 5 seconds will reset the condition and everything works fine. Any ideas.
P.S. I assume the trouble light from the vehicle means a code is thrown from the vehicle (I have no code reader).