Did the car sit on the lot for awhile and the battery allowed to discharge completely..? My dealer told me a couple of years ago they had this problem with the batteries and have since added a re-charge routine.
Apparently these batteries don't do well if discharged over time.. they had to replace a number of them.
Lawrence.

 

I think a lot of dealers just replaced the battery because they didn't know what else to do. Of course, replacing the battery solved the problem, but only because that automatically resets the energy control module.

 

That certainly could be the case.. I was however responding to a question of, if the 'reset' is not working, what else could it be..
I've been lucky so far, with both my F and the XE not to have any battery problems.
Lawrence

 

As Dave mentioned, the only circumstance that I can remember where the reset didn't work for a forum member, was due to excessive paint on the battery lead grounding lug at the chassis.

 

One curiosity to me is that I have never needed to do the reset procedure even though I have had a couple of upgrades to the system that, with some other members cars, would have caused a problem.
Lawrence

 

Indeed. Some cars have the issue, and others don't. It probably is a real flaw with specific units, but given the simple resolution, it just isn't worth going into battle with the Jag dealer over it.