Toyota 2013 Prius Owner's Manual page 290

2-2. Instrument cluster
Shift position indicators
(→P. 245)
*
1
: These lights turn on when the "POWER" switch is turned to the ON
mode to indicate that a system check is being performed. They will
turn off after the hybrid system is on, or after a few seconds. There
may be a malfunction in a system if a light does not come on, or if the
lights do not turn off. Have the vehicle inspected by your Toyota dealer.
*
2
: The light flashes to indicate that the system is operating.
*
3
: The light comes on when the system is turned off. The light flashes
faster than usual to indicate that the system is operating.
264
PRIUS PHV_OM_OM47787U_(U)
"AIR BAG ON/OFF" indicator
(→P. 198)