Hi
In most of the new cars, there are build in Follow me type lights, and as many things in Xantia that are out of the list.
My first "hack" was to add relays to Low / High Beam Lights and to take the amperes out of the stalk switch in the cabin. What i have done was first to remove the original 10A fuses (A1-A2, B1-B2)
On A1/B1 pin are the relay controls, from relays out via 10A fuses goes to A2/B2.
Later on(few months), it come the circuit for "follow me", based on NE555 timer and variable resistor.With the second one you can change the delay based on: T(sec) = 1.1xR(ohms)xC(farads) or in my case:
T(sec) = 1.1 x 80 000Ohms x 0.00047Farads = 41.36sec
Maybe the circuit is far from perfect but do the job. Feel free to test,modify and use.Good luck
Actually there are Chinese crystal front lights for Xantia II and probably with them and xenon bulbs will be much better but.. since in the past i have bad experience with DEPO main beam lamps.. somehow do not with to give around 300e just to find is shit or in Katsustus some nice dude to write down - non original, to be removed 
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