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That is usually the BCM. It's the little double-circuit board behind the interior fuse panel. There are 2 relays on the board that can stick, or some had bad solder joints that fail. There are a couple youtube videos showing how owners repaired theirs. The advantage is it's cheap and the unit will still be recognized by your car.

If you don't care to repair, you can buy a new or used BCM. Once a different one is installed, it must be "registered". As I understand, the car won't run until this is done. All dealers and most shops have the gear to do this procedure.

The stereo, BCM, ECM, etc, on modern cars talk to each other on a network (CANBUS). Registering is sort of like identifying a new IP/MAC address, so other modules recognize the new equipment and know how to talk to it.
 

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Many thanks for your kind information. If you have the YouTube link to pass me, I will appreciate.
 

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This part 1 of 4.
This shows disassembling the boards.

In Rob's video he uses common logic. It can be bad wires, headlight stalk, etc, but with Fiat it's usually those relays. In the second video, had had problems de-soldering the relays... probably because it's coated with lacquer or plastic. You can follow his method or use a Dremmel to grind the solder joints slightly.
 

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Headlights won't turn off
Before pulling apart anything, replacing any module. These cars run off software. Every component on the car. Get your self a code reader. See if you can pull any codes off the cars CPU. You car may just have some corrupted software. That’s affecting the headlamps from shutting off. You may have to visit a Fiat dealership to correct the software.

Good Luck.
 
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