The arrows will flash in unison with the exterior turn signal, when using the turn signal lever.
See also:
Maintenance Procedures
The pages that follow contain the required maintenance services determined by
the engineers who designed your vehicle.
Besides those maintenance items specified in the fixed maintenance schedule,
...
Installation of electric/electronic devices
Electric/electronic devices installed after buying the car or in aftermarket
shall bear the and marking:
Fiat Auto S.p.A. authorizes the installation of transceivers provided that installation
...
Left-hand direction indicator
The warning light on the dial turns on when the direction indicator control lever
is moved downwards or, together with the right indicator, when the hazard warning
light button is pressed. ...