[NonWonderDog]

I found a manual here, and here's what it says about it:

On all airplanes equipped with outer wing tanks,
two low level warning lights are installed on the for-
ward left-hand side of the cockpit. These lights auto-
matically come on when fuel for approximately 5 or 6
minutes of engine operation remains in the tank.

I'm not sure it's very important, since we don't actually have to do any fuel management ourselves. I have no idea where those lights are mounted, either.