This before start check of TOWS only says the system is working and the annunciator works. It can not be tested for all the faults like trim, speedbrakes and flaps, only that something is wrong. Flaps are always up during this check so that is the fault giving the warning most of the time. Hopefully this warning will never be needed again since we are aware of the possibility of failure of the system and the importance of checking flap setting lining up with the runway.