I don't know what year you have but my 97 manual shows 3 fuses for the clock. The 15A dome light fuse provides constant 12V to the clock. The cigarette lighter 15A fuse provides 12V labled "power for indication", which means it turns the numbers on, I think. The 15A tail light fuse provides 12V for "signal of indication" which may be background lighting when the lights are on? Seems the translation from Japanese leaves a little to be desired.

1997 T-100 4X4 Xcab,Warn Hubs
02 Camry LE
2008 Yaris