TOD Check Light on 1998 Acura SLX

My TOD Check light comes on occasionally when in 4WD. 4WD seems to work fine. The light usually goes off and stays off when in 2WD. What could be the issue?

2 answers
Problems with the Engine/Transmission/TOD/ Air Bags are all diagnosed using a scan tool plugged into the 16 pin diagnostic socket under the dash. I have no personal experience of TOD problems.
why my tod check light on when in 4wD ? Mt car Acura slx 1999