Transmission oil light

[Purplewillie]

I posted this on BNO as well,just looking for suggestions on both boards.
My trans oil light has been coming on every time I start the bus. Never came on when we picked the bus up or on the 2 day drive home. My bus has had a v730 put in years ago so I'm not 100% sure if its even connected to the transmission. Where would it connect to the trans?
Trans fluid level is full and my understanding of the transmission low oil light is that it shouldn't work until the trans is up to operating temps. Mine is coming on as soon as the 8v71 fires up, stays on for 45 minutes or so of driving then flickers and goes out.
Anyone have any ideas what I should be checking? Transmission has oil,seems to shift ok,65 + mph in high gear. Maybe a filter plugging up?
I'm stumped at the moment, I am accepting suggestions on things to check....
Thanks   Mark