Why does my light on (D) drive blinks while I am driving?

on 1994 Honda Accord

When I start driving it stays steady but after a fews or 5- 10 minutes later it will begain flashing

Have a scan test of the transmission control module performed.... constant/rhythmic flashing is a indication of a trans fault... Honda Tech here can explain in more/better detail...later on....
Oh , the pressure!!!!!
2 more answers , 1 more comment
As pushrod stated , it is an indication of a fault detected in the trans. Have it scanned (NOT a code reader!), Depending on mileage and general condition of trans. it could be anything from a simple pressure switch , to a code 'P0740'. Whatever it is post the specific DTC(s) on a reply here and I can offer some suggestion on what to do.
I am only aware of two reasons that lights will blink on and off,( except for the obvious turn and "e" flashers).
1.The ground on the light bulb is not making good contact.............
2.The element, this is the little squiggly wire inside of the light that illuminates when current runs though it.
The element becomes detached and when the bulb is moving the element intermittently connects and disconnects causing the light to act like a signal light, except that it would flash erratic.
SERIOUSLY???????? ..............JUST KIDDIN'............HAVE FUN.