I now have a couple weeks of ownership on my 2006 XJR. I have fixed a couple small items; lubed doors and handles, struts for hood and trunk, tranny filter and flush, rearendush, power steering flush.
This weekend we had monsoon rains. Pouring sides rain. The parking brake code came up on the dash. Restarting car would clear it. Parking brake was intermittent. I hopes few days without rain will resolve. Seems fine now.
I plan on having rear calipers pulled and installing new guide pins, boots, and clips. What should I look for in the parking brake.
The little radio selector next to the cig lighter, which is not shown in the owners manual is not powered. Is there a trick to this?

 

Have the battery load tested. You might find your car still has the original battery installed.

 

I had been working on the car. It did crank slow when this problem appeared.
The battery is huge and looks new. It will look to see if age is determinable. Plus clean posts.
I looked over before purchase and it appeared to be a recent install. But it did pull down after a few hours of doors, hood, and trunk open.

 

these cars need healthy voltage or random codes will surface (like park brake fault) with mediocre voltage. You need at least 12.6V or trouble will be apparent. Check the date code on the battery, especially if it's a Jaguar battery or Varta (date code on neg post) ex: 08 - 04 (would be 8th week of 2004)

Feel better knowing your issue was probably a partially drained battery..