When I drive my XJ8 Vandenplas 2004 and my XTYPE sportwagon 2004, there is the same symptom; I heard some clicks and pops just under the front seat's passenger. I checked it but its truly difficult in the xj8 to see
the culprit.

 

could just be the module is loose, or perhaps cracked housing. I've heard other members find that the seat module is only held on by one screw, the other came out or broke its mount. Unscrew the rail bolts and tilt that sucker up for a good inspection.

 

If the module is cracked don't think about trashing it. They are impossible to buy.

 

Thanks a lot for your answers. I will do all my possible about that. Did I do something before I unbolt the seat, I mean that I know there is an inflate device in the back seat?

 

No you don't need to do anything spedial. The bolts are torx head and there is an expecially thick washer you need to keep. After you unplug the wire, the seat can be lifted out.

 

I just had the seat control module out of my 99 xk and it had FORD all over it. If yours says the same maybe the Ford dealer might have a new one.

 

Mine says ford all over it also. I still could not find one. I ended up jumpering in a switch. I don't know what the computer memory will think about that. So far so good.