I saw this thread yesterday on the Disco forums, well worth adding a link in here in case any one else finds this thread searching for battery drain.


http://www.disco4.com/forum/post1366423.html Porsche 911 (996)
2015 BMW 5 Series Touring
Not got a LR of any kind at the mo, and got itchy feet.

Great link. Just ordered a clamp meter. Oh boy! More tools I'll never really master.

So if my door lock actuator is "broken" as iidtool says would this prevent the vehicle from going into sleep mode?

Finally found the problem turned out that the so called auto electrician had not checked the alternator properly took it out today and replaced the faulty regulator with a nice new one and it is now charging properly, also had to do the o ring on the eve cooler which was leaking as well, found the battery drain which turned out to be a damaged wire which had rubbed on the chassis so that is now sorted so it hankyou for all the help guys you are all stars 🤗👍👍👍

Excellent news glad it is sorted

Glad yours is sorted, my 2002 4.4 petrol saga might be continuing. Interior lights were flickering and fully charged battery wouldn’t attempt a start after three days sat on the car, EAS inactive etc. Alternator charging voltage typically 12.2 to 12.5v. Alternator tested and found intermittent, indy fitted exchange Bosch from Germany which has cured flickering and now charges at 14.5v. Also replaced Blowers resistor as a precaution. Car started fine this morning but this afternoon it only just cranked enough to start. Drove 10 miles to indy and got replacement battery at 4pm. Oddly the old battery was at 13.6v when taken off the car. Drove 25 miles home uneventfullya but noticed air suspension inactive message appeared as I turned the engine off. New battery at 12.6 v with engine off, will see what tomorrow brings.
Strange thing is I have the old battery and it is still sitting at 13.6v at 8pm. Anyone come across a failing battery with a high voltage before? Is higher than normal voltage indicative of an internal battery fault? I’ll see if it degrades over the next couple of days.

I have just replaced the lead from the battery to the alternator and starter the lead was expensive at 120 odd quid as it comes remade with fixings etc - mine was done as preventative maintenance really after speaking to an indie who suggested it- my old p38 suffered from intermittent starting etc and it was corrosion internally in the leads from the starter to battery got round it by putting a second cable from the starter to battery - cost 6 quid
Not saying that this is your cause but when I removed the old cable from the fatty all the terminals were heavily corroded didn't test it as having just spent the money on new one didn't want to be disappointed by finding out it was ok
Any worth a try testing the connections and what you are getting through the cable

Good point. I had the indie check all main earth and positive connections, he repoted some corrosion so all were cleaned up. I haven’t checked the lug to cable connections yet though, retermination may be on the cards.
Battery voltage this morning was 12.47 so dropped a bit overnight, going to leave it standing over the weekend and see what it does. Old battery now 13.06 which seems surprisingly high still.

Sat in the locked car with interior alarm off. Car didn’t go the sleep and the sensor fan stayed running for over an hour. Curious thing, every minute there was a click behind the hvac panel and the fan stopped but immediately restarted. Also curious is that it was 5 seconds out of synch with the car clock over one hour so I presume it uses an independent timer.
Anyway, got out and locked the car the same way and had tissue on the fan. Checked after half an hour, the car was asleep and the tissue had dropped. Indie had done the tissue test too and said it passed. Can the hvac sometimes shutdown and sometimes not?
Read elsewhere on this forum about a trick to interrupt the feed to the hvac panel (fuse 12 I think) so that’s tomorrows job.

Just to close my input on this one, before I got to do install the relay the rad blew so I had it recovered to my indie. Whilst it was there he called to say he’d found someone with one new sub-harness to do the official modification to the HVAC, last one on the shelf. Three days of testing later and it appears to have solved it 😀. Hope it stays that way!