My wife's '02 S-type battery recently started draining. 720 ma draw. Isolated it to cartridge fuse 25 in the trunk and from there to mini fuse #20 in the cabin. If I pull that fuse then hook my amp meter between the negative battery post and the negative cable, I get only a 38 ma draw. Also, When I put the key in, I can turn it from 12:00 to 2:00 before getting resistance. I thought that might be the problem so I removed the ignition switch assembly and get the same results on battery draw with the switch removed. The fuse in question powers the General Electronic Module, Rear Electronic Module, HVAC controls, and Instrument Panel. My radio plays each time I hook up the amp meter, so I have to turn it off. Battery has over 12 volts so it should be OK for this testing. Does anyone have a next step? Does the slop in the switch or the radio mean anything? Thanks.

 

I think the actions of the radio and key are normal as you've described them.

Have you seen this description of the current drain testing process?:

https://www.jaguarforums.com/forum/s...-drain-123535/


Specifically, the car has to sit undisturbed for about 45 minutes before all of the computer modules enter sleep mode. Opening a door or pulling/installing a fuse will wake the car back up, at least partially.

I am very partial to the test method mentioned in posts #3 and #9. You don't have to disconnect anything or pull any fuses.

 

Ditto on the key slop being normal from my experience also ,...the only thing I know of with the ignition switch, is if the flap does not return to it's home position some electrical components stay live ....there is a tsb I believe that covers that scenario

 

Ooh, excellent point. Easy to test, too. On my '02, when I remove the key, the driver's seat moves fully aft to make it easier to get in and out of the car.

If you already have the seat adjusted all the way back, you won't notice if this function were to fail. To test, simply move the seat forward a couple of inches. Remove the key and make sure the seat moves fully aft. If not, a failure of the key flap switch is the most likely culprit.