Turn the knurled ring to 
.
The warning light 
on the instrument
cluster will come on.
See also:
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
...
Reactive Head Restraints — Front Seats
The front driver and passenger seats are equipped with Reactive Head Restraints.
In the event of a rear impact the Reactive Head Restraints will automatically extend
forward minimizing the gap bet ...
Additional braking light (third stop)
To change the bulb, proceed as follows:
❒ open the tailgate and loosen screws (A);
❒ release the clip (B) and open the bulb holder, the remove the bulb (C) to be replaced
(clippe ...