Parasitic drain

santinif4 · #1 01-20-2017, 08:42 PM

Hello - I have had the dreaded parasitic drain issue on my 2005 X5 4.4 for some time now and have possibly fixed it. After researching the forum and reading the many posts on possible causes and solutions, several culprits consistently showed up at the top of the list. FSU/FSR (final stage unit/resistor) and the TCU circuit were both very likely culprits, so I decided to try the easiest first, which was to simply pull the fuse for the TCU which is not used anyways.

The vehicle would normally be dead after 5-6 days if not driven. It has been 8 days now, and I have been able to start it for the last 3 of those 8 days so far. I don't drive it or let it run( so as not to recharge the battery in any way) and it may be that the TCU circuit was the problem after all. I hope I am that lucky.

My question for anyone that knows is what else is on that fuse that I pulled for the TCU circuit (I believe it was fuse 74 in the panel in the rear right trunk compartment)? If there isn't anything else powered by through that fuse I may be good to go, but I just wanted to make sure I wasn't losing some other feature/device on that same circuit! Can't find any schematic for it...

Thanks !

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Rockstarsi · #2 01-20-2017, 08:44 PM

I believe I have the same problem and it cuts the cd/radio function. Let me know if you get past it

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80stech · #3 01-20-2017, 08:52 PM

There is always going to be some drain on the battery so you have to be careful not to go on a hunt for a drain when the problem might be a poor battery.

santinif4 · #4 01-20-2017, 11:02 PM

Thx for replies - the battery is 9 months old and I had it deep charged and tested at Interstate batteries and they said it was a good battery. I forgot to mention it does not have the navigation screen. The radio and CD player both continue to work even with fuse 74 pulled. Does anybody know what else is on that fuse circuit? Anyway to get a schematic? Thanks

Emory39 · #5 01-20-2017, 11:35 PM

are you the one with the black X5 with the dinan exhaust?

upallnight · #6 01-20-2017, 11:38 PM

Fuse 74 which is a 10 amp fuse is for the telephone. So if you don't have the old analog telephone, removing it shouldn't harm anything. Perhaps the phone connector at the back of the trunk on the left side is shorting. It looks like an old DB 25 serial connector.

wpoll · #7 01-21-2017, 12:02 AM

There are full wiring diagrams here: -

WDS BMW Wiring Diagram System

You'll need to install an Adobe plugin (SVG viewer) and you'll need Java, with a site exception for bmwtech.ru to get around Java blocking.

santinif4 · #8 01-21-2017, 12:25 AM

Upallnight thx - so fuse 74 is in fact labeled 'telephone' on the right rear compartment. It has nothing to do with the TCU then? I thought I had read on other posts with this intermittent slow drain about how pulling the TCU fuse might solve the problem and they referred to it as 74. Confused now... (again)

The whole TCU/BT option is pretty fuzzy to me

And Emory39 - sorry not me in the black X5...

Fifty150hs · #9 01-21-2017, 12:42 AM

recently had the same problem. turned our to be the telematic (blue tooth) wasn't shutting off. drained the battery over night. Removed the telematic, no more problem.

Emory39 · #10 01-21-2017, 12:50 AM

Quote:

Originally Posted by wpoll

There are full wiring diagrams here: -

WDS BMW Wiring Diagram System

You'll need to install an Adobe plugin (SVG viewer) and you'll need Java, with a site exception for bmwtech.ru to get around Java blocking.

what internet browser are you using? I can't access the menu. Did you did any mods to your security /

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