[georgerazvan]

Hi everyone!

My car model: BMW F34 xDrive

A few weeks ago I saw for the first time “Starter/Ignition fault” error. I changed the starter. After a while I repaired the alternator because I got “Battery is not being charged” error. From time to time there was a wire burnt smell inside the car, but only for a second. I think that smell is from the alternator(if that will be a wire that should smell all the time isn’t it?).

Now after a few weeks my car is not starting. I got the “Starter Ignition fault” error but it starts if I get a boost for the battery from another car. Trying to start it again and again, now the battery is drained. I changed my battery 2 days ago with a new one, I registered it and the problem persists, it works only a few hours but started only helped by another car boost.

What should I do? could be the IBS and it needs to be replaced? could be the alternator not charging the battery while driving even that was repaired? but if yes, why I get the “Battery not being charged” more than one second and that’s it? I measured and the voltage was right when started, then 14V+. Also before starting 12.3V+.

My model does not have a fuse for start stop, so I eliminated the possibility that can be the fuse itself.

[Ragnar The Redneck]

The only help I can offer is if you cross post here:

https://f30.bimmerpost.com/forums/fo...play.php?f=437

It is the technical forum, Mechanical Maintenance and TSBs: Break-in / Oil & Fluids / Servicing / TSBs and Service Bulletin.

[alainv1029]

OP, I’ve been going through sort of the same issue. Mine is 2015 F34 GT. It seems to only happen during the winter months when the heater is active. I usually set my temp to 68-70. So during the winter months, the car would make some sort of humming/buzzing sound after ignition is cut off. I’ve deduced it to the water pump. So I would come out in the morning and the car would be dead and won’t start. After jumping with my Noco, and car is running, I run Carista or BimmerLink and battery state of charge would report 99%. Yet car didn’t want to start. No dash lights, nothing. The alternator is working fine as it does charge the battery while driving. No burnt smells of any kind. At my wits end as well.

My dealer wants $509 to diagnose. And I’ve replaced the battery with oem.

[Billfitz]

Water pumps that run when they shouldn't and as a result drain the battery are well documented.

[georgerazvan]

Originally Posted by Billfitz

Water pumps that run when they shouldn't and as a result drain the battery are well documented.

which water pumps? because as alainv1029 said, I hear a vibration when trying to start the engine, also a lot of times I remember I heard that sound when in the past I shut the engine off.

[Billfitz]

There's only one water pump, the one for the cooling system. Another source of humming noise when the car is unlocked and after it's shut off is the low pressure fuel pump. I haven't heard of that causing parasitic power drain, but the water pump is one of the two most common sources of power drain. The other is the dashboard.

Search 'BMW water pump killing battery'. You'll find dozens of hits, some of them in this forum.

[georgerazvan]

Update: I measured the voltage again. It is 12.3 before start and 11.5-11.9 after a jump start. And today is a weird sound from the alternator. I will change it, probably that was soft repaired.

[georgerazvan]

I tried to jump start the car from the trunk battery but the software does not allow that. Someone said to me it’s possible because that is detecting a bad alternator and its preventing engine to start. But it works from front terminals.

I wonder if a bad alternator can cause issues on starting, even I rechearged the battery. I suppose there can more issues than that single alternator problem.

[georgerazvan]

UPDATE: changed the alternator, still same. Measured the alternator directly, it has 14+ volts but the battery terminal both front and rear has under 12V. Probably some break cable won’t let the battery to be charged.

I would measure those but I can’t find an electrical schema.

[Oksamit78]

Originally Posted by georgerazvan

UPDATE: changed the alternator, still same. Measured the alternator directly, it has 14+ volts but the battery terminal both front and rear has under 12V. Probably some break cable won’t let the battery to be charged.

I would measure those but I can’t find an electrical schema.

The main cable from front (+) terminal is this one (item 1):
https://www.realoem.com/bmw/enUS/sho...diagId=12_2042
But something else could be at fault...

Since you get +14V on alternator direct and depending how old is your F34, as precaution you should check the ground cable between engine/transmission and the body of the car. It could be old and corroded and thus causing abnormal electrical resistance that could cause the +12V at the front and rear terminals.
Example based on F34 340iX (Items 2 and 3):
https://www.realoem.com/bmw/enUS/sho...42#12427614083

Then, next thing to check (because you can start the car by boosting through front terminals):
The positive cable that goes to the back (Item 2):
https://www.realoem.com/bmw/enUS/sho...diagId=61_2891

[Billfitz]

The time is long past when you should have employed the services of an expert mechanic, who would have tested the starter and alternator to be sure they were broken before replacing them, and tracked down the source of your parasitic power drain.

[georgerazvan]

Originally Posted by Oksamit78

The main cable from front (+) terminal is this one (item 1):
https://www.realoem.com/bmw/enUS/sho...diagId=12_2042
But something else could be at fault...

Since you get +14V on alternator direct and depending how old is your F34, as precaution you should check the ground cable between engine/transmission and the body of the car. It could be old and corroded and thus causing abnormal electrical resistance that could cause the +12V at the front and rear terminals.
Example based on F34 340iX (Items 2 and 3):
https://www.realoem.com/bmw/enUS/sho...42#12427614083

Then, next thing to check (because you can start the car by boosting through front terminals):
The positive cable that goes to the back (Item 2):
https://www.realoem.com/bmw/enUS/sho...diagId=61_2891

Thank you. My F34 is from 2015.

I checked the ground strap but it looks good, but I will ask when I will contact the service in the next days.

One new thing I found is that the terminal wire is too hot, it almost fried my skin

[georgerazvan]

Originally Posted by Billfitz

The time is long past when you should have employed the services of an expert mechanic, who would have tested the starter and alternator to be sure they were broken before replacing them, and tracked down the source of your parasitic power drain.

It’s a lack of professionals in my area and we had the Christmas holidays when all people has a lot of days off. But for sure I will contact a service.

[Oksamit78]

Originally Posted by georgerazvan

Thank you. My F34 is from 2015.

One new thing I found is that the terminal wire is too hot, it almost fried my skin

You should replace that wire. It is not normal for it to be that hot.

[Billfitz]

+1, a hot wire or connector indicates trouble. It could be the wire has been damaged, it could be what's on the other end of the wire is drawing far more current than it should be.

[georgerazvan]

SOLVED

I can’t believe I spent that time and 500$+(only this time - but $1K+ in total from the first issue) on this. It was the bolt and the terminal from the front-right side under the hood. The bolt was not properly fixed and both cable and contact surface were dirty.

I used a contact cleaner spray and sandpaper and it started without any problems even the battery was discharged. At the first look on System Voltage under secret menu I saw 13.2 but after a 30 minutes drive it is now 13.7. I think is normal thinking the battery is discharged a bit. Will come back to normal after a longer drive.

Thank you all for your advice!

[Oksamit78]

Glad you've got it resolved.

[Donnydarko1]

Glad you got sorted, I have same issue started yesterday, which bolt was it? Could you send a pic please.

[Donnydarko1]

Was it the bolt you charge car from? Thanks

[Oksamit78]

Originally Posted by Donnydarko1

Was it the bolt you charge car from? Thanks

It did sound like that was the bolt and connection to the charge terminal.