Guess the light flashing on the panel

[drb1966]

I've run out of guesses. It is labeled "pilot" and is flashing while the bus is running. I've never noticed it before. The side sign operates as normal, the back door sensor seems to operate normal. I don't a service manual and I can't figure out what the lights indicates. Its a 2001 if that helps.

Thanks

Trying to add a picture if I can figure that out