I'm not sure about this, I haven pushed the switch several times when the tank been empty so maybe.
Try reseting the system by either disconnecting the battery or removing fuse 24 for 30 minutes and see how it goes.
When my sub light goes off indicating empty I can hit it again 4-5 times and it comes back on for a short while then goes dead till I fill her again. (Ute)
2002 4.2TD ex Telstra