F430 headlights

You can probably figure out some of the operation based on the number of wires on the lamp and power supply.

If the lamp only has two wires on it, it's not using a dual element lamp to increase the brightness for high beam, rather, it's the power supply putting out a higher voltage.

Unfortunately, Ferrari 456, 360, 430, etc, Workshop Manuals available to the general public don't include things like component internals, relay & relay panel internals, column switch wiring, etc, making diagnostics rather difficult.

Since I believe you haven't changed a lamp yet, all I can suggest is doing resistance checks on the lamp or the lamp harness pins if that is easier to access, observing the necessary precautions when dealing with high voltages. Power supplies may take a while to discharge after power has been removed.

 

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Your 430 headlight has xenon bulbs with a ballast, my recommendation to analyse the issues is as follow:
1. Check the input voltage on each ballast, this should be more than 12 volts. if the input voltage is lower, the xenon bulb might not 100% ignite and keep flickering as the ballast continued trying to ignite the bulb.
1a If the input voltage on the ballast is lower than 12 volt, you need to check your battary voltage first, this should be higher than 12V
1b if the battery voltage is OK than you have a wiring problem. the start / ignite current of a single ballast can be easily 8 amperes.
1c disconnect one of the ballast, try to check the headlight separately, by doing this you limit the total start / ignite current to the battery


2 if the input voltage on the ballast is Ok you can swap the xenon bulb and test one headlight at the time by disconnecting one ballast. i.e. verify if one of the bulb is also OK.

If doubt that both ballast are broken.