Toyota 2003 Prius Owner's Manual page 168

If the indicator or buzzer comes on...
(h)
(i) or
(j)
(k)
(l)
(m)
(in red)
(n) Key reminder buzzer
Shift position
(o)
reminder buzzer
Stop and check.
Take vehicle to Toyota dealer. If brake system warning light is also on, stop immedi-
ately and contact Toyota dealer.
Take vehicle to Toyota dealer immediately.
Close all doors.
Fill up tank.
Stop and check.
Remove key.
Put the selector lever in "P" position.
Do this.
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