Lexus 2013 IS250 Owner's Manual page 204

202
4-2. Driving procedures

Turn signals can be operated when
The engine switch is in IGNITION ON mode.

If the indicator flashes faster than usual
Check that a light bulb in the front or rear turn signal lights has not burned out.

If the turn signals stop flashing before a lane change has been performed
Operate the lever again.

Customization
The number of times the turn signals flash during a lane change can be changed.
(Customizable feature P. 549)
IS250_EE(OM53B11E)