I redid the battery drain test reported here: https://www.jaguarforums.com/forum/x...-drain-193889/

I used a screwdriver to close the latches so the computer thinks the doors/hood/truck/doors are closed.

After 17 minutes after setting the alarm, the ammeter stayed at 150 ma for 60 minutes.

I pulled fuses until I found the culprit that lowered the draw to 30ma: "Radio/cassette head unit"

BTW- There are a number of fuses that reset the sleep timer and you'll need to wait 17 minutes before continuing the test. Anything like 'door lock sensors' or 'alarm'.

So the good news is maybe I don't have to charge the battery before driving my car, the bad news is: how can the radio head unit discharge the battery when it shouldn't be getting power when the car is parked?

I did replace the "Accessory power" relay in the passenger compartment fuse box as a test before today's ammeter test, so I don't think that relay is leaking power into the head unit.

What have I missed? Thanks!

2000 XK8 Coupe, 99K miles.

 

There have been reports that the amp relay goes bonkers and it does not shut down.

 

Have you checked the little trap door on the ignition key hole? It has a reputation for getting stuck, so the car "thinks" the key is still in the ignition and leaves the radio on. Easy to check, cheap to fix too.

Best of luck, keep us posted.

 

Yes, I had previously investigated the trap door and it looks fine.

The radio and nav stopped turning on a few weeks ago, so it's both puzzling and suspicious that removing the fuse for the radio lowered the drain from 160m to 30 ma. If the leak is in the head unit, it should not be powered when asleep.

I also previously replaced the relay in the passenger side interior fusebox, which I believe is the relay for "Acc" - Accessory power circuits.

What explanation explains this combination of symptoms? I'm puzzled.

 

Update: Replacing the radio head unit fixed the radio and sat nav, and presumably the drain too.