Recently lost all electrical functions, Boot lights out, no start, windows didn't drop, etc. Cleaned the terminals, tested battery with a Midtronics 200 battery tester, over 800 CCA with 12.5 volts. No improvement until touching negative to positive terminal, light in boot turned on and normal functions restored.
I didn't trust car so let it sit for several weeks (5), tried to use today, no power so started with a battery charge, tested battery again 810 CCA 12.8 volts, no joy. Checked battery cables center post to outside edge of connector and to the ground point on the chassis, all OK no voltage drop. Still no functions, touching negative to positive and everything now works.


Is there a battery shutdown mode?

 

Sorry
2003 XKR 34K