Right, my low mileage X350 XJ6 has been playing up with that old chestnut, the P1638 canbus fault code!
I get the dashboard lighting up like a Christmas tree, the gauges die and the indicators and brake lights stop working. I do however only have one fault on the screen, which is "Parkbrake Fault" and no limp mode. The EML light comes on and stays on!
So far I haven't looked at too much, but I did pull the plastic cover of the slam panel to check the integrity of the earth's behind the headlights. They are attached to the bodywork securely, although they do look a little dirty, so I'll be cleaning them.
As regards the electronic handbrake, I put brand new pads in it to see if it would cure the problem (it didn't) and checked to see if all mechanical and hydraulic parts were free, which they were.
So has anyone out there in Jaguar land had similar problems and can you give me any guidance as to where to start?

Thanks in advance..

 

Firstly, what is the age and condition of the battery? A failing or weak battery can cause some of these mysterious electrical 'gremlins'.

With the ignition in the off position, what is the voltage at the battery? If it is 12.2 volts or less, the battery must be replaced.

 

I forgot to mention the fact that it's got a brand new Bosch battery on it..

 

Notwithstanding, what is the voltage at the battery with the ignition in the off position?

 

12.6 volts, 14.2 volts at tickover.
Exactly the same figures as my XJR and everything on that works just fine!

 

I got bored with trying to solve this problem, so I sold the car on, faults and all!