Battery drain ... fuel system related

[Johnsi02]

Hello,
Car is a 2007 X5 SE 3.0d 235bhp.
I have a weird fault and would be grateful for any thoughts from people much smarter than me.
Quick description: I am trying to narrow down a battery drain.
It appears that the car not going fully to sleep and powering down completely as it should.
The key obvious symptom is that the fuel pressure valve located on the high pressure fuel pump is activating even when everything is shut down. The solenoid switches on and off constantly making a loudish buzz. Interestingly, it doesn't do this after the battery has been disconnected, only after the engine has run and been turned off. I'm wondering if that's because the DDE has been reset by the battery disconnection. Unplugging the pressure valve when it's misbehaving has proved that this is the the culprit. Narrowing down sounds in the engine bay wasn't the easiest of tasks, mind you. It's possible, of course, that other systems are staying awake but are not as obvious.
But it seems that only some systems are staying awake. For example, the LED for the 'P' indicator on the auto shifter goes off when you'd expect it to after 15 minutes or so.
There's no obvious codes showing up that look like they are relevant.
I'm running out of ideas, to be honest.
Have ordered a new circuit cut off relay for the rear fuse box as this is getting warm and I'm a bit suspicious that it isn't functioning properly although I'm not sure that it is related to powering the DDE or the fuel system.
I did find a thread on a forum in the USA describing the exact same scenario but, annoyingly(!), there wasn't a conclusion that described the solution.
Any ideas gratefully received.
Ian.

[Johnsi02]

Hi ...still no joy!
Replaced the relay. Still the same symptoms.
Any ideas?
Ian

[Greydog]

I have just replaced the Terminal 30g relay in a friends E70 which was suffering battery drain, the 30g terminal was showing up on ISTA as faulty.
It seems to have cured his issue, the replacement was through a BMW Main Dealer and seemed to take ages to arrive

[Leslie]

The solenoid wouldn't switch of after the battery is disconnected as there would be no power to energise it if that's what you mean . Given whats happening there has to be a code and you need to get a code reader or get someone to do it for you. The high pressure fuel pump may possibly be faulty but they are generally very reliable so that's unlikely id have thought.
Are you sure the battery is actually good given a failing one can cause all sorts of weird issues ?

[Johnsi02]

Thanks for the replies. Very much appreciated
Investigations continue tomorrow!
Ian

[Johnsi02]

Update ..... I almost don't want to write this for fear of jinxing things .
But my battery drain problem seems to have been sorted.
After an endless process of elimination the culprit appears to have been a faulty driver side window/mirror switch panel. There was no code fault thrown up by this which I find surprising. My working theory is that the unit had a short in it. The unit, according to my research, talks to the Footwell Module and this in turn communicates with the CAS. I'm definitely no expert but I suspect that there was a constant signal from the switch that was keeping the modules active.
Since swapping out the switch panel the car is going to sleep properly and the voltage on the battery after leaving the car overnight is sitting at 12.5v. Luckily I had a spare switch panel from a previous project.
The solenoid that was cycling on the high pressure pump is silent and the circuit cut off relay in the rear fuse box that was constantly warm (signifying that it was permanently energised) is now behaving normally.
There's no doubt that these cars are complicated beasts and electrical gremlins are just a fact of life.
Thanks for the previous replies. I really appreciated you trying to help.
Ian

[X5Sport]

Fingers, Toes etc crossed.

I don’t remember that particular ‘gremlin’ ever coming up on here before. I doubt many of us would even have thought of that one!

These cars are very complex and annoyingly not every module has the ability to tell you there’s a fault on part of the system that’s keeping me awake.

[Leslie]

Great fix id never have thought of it