NJohn_Cook

I also have a '52'plated 2.0 Xsara HDi (90hp model) like you I changed out the factory fitted radio cassette thing for a shop bought one. As you rightly pointed out there are several wires that are now not connected to any thing, these are for the stalk controls, however, I have not had any issues concerning the main headlights. I changed out the radio over 4 years ago, so I'm assuming the lighs issue is not related to the radio. Hope that helps.

Not much of a help to you, but I'm having a similar problem. recently changed the alternator, garage claims it's not quite charging at the correct level, I dissagree. but if I leave the battery connected over night it drains it. I have even tried starting from a fully charged battery, volts meter reading 13.60v when installed but left connected over night it drains the power away. Alternator reads between 13.5v and 14.6v across the battery at idle. I figured that there might be a short causing a drain somewhere. At least it's easy to disconnect/reconnect the main battery lead, However, it's darn frustrating. so any help for both of us would be appreciated.