Providing there are no signs of a leak from the transmission then there is no need to check let alone top up the box. This is not really a DIY job as ideally needs to be on vehicle lift to take off the under-shield and gain access to level bung. Low fluid will skip into a false neutral on corners and will improve as it warms up. Do not drive like that as permanent damage will result.
mags
May 2010
Automatic Answer
We may have found other answers which could help you.