My car will soon be stored and I really don't worry too much about heated seats....but this is odd. My wife was in the car with me the other evening and turned on the heater for her ( passenger ) seat. Shortly thereafter my (driver's) seat got warm as well ! I pressed the button for the driver's seat heater and nothing happens at all.

So, it seems that the switch for the passenger seat heater operates both heaters. Has anybody heard of this before ?

 

Yep. Happened not too long ago to my 2004 as well. Exact same thing.

For me it was a poor connection under one of the seats. Try reconnecting the two plugs under each seat and see if that helps.

 

Interesting. I will check that out. My passenger seat module is from a non memory type from an XJ...maybe that is the issue