335i Battery Short/Wake-up line error.

[Atunker]

Hello everyone,
I have a 2012 BMW 335i sport line trim that I purchased a few months ago and have really been enjoying. It is a higher mileage car (135k miles) that I do use as my daily/fun drive able project. I’ve been getting the “Battery discharging while stopped” error since I purchased the vehicle and I’m trying to narrow down where the issue is. My daily commute is about 20-25 minutes each way to work, and am driving in warm temperatures in this southern heat so I don’t think it’s short commutes or temperature. It seems that the car shuts off many of the convenience features after several minutes (like Auto Unlock when touching the handle, etc) to preserve the battery. I noticed that the start engine button backlight never goes out and will be on all night. I throw a battery charger/maintainer on about once every 3 weeks as the battery voltage low warning comes on after several weeks. There were several bad sensors shorting and throwing codes including the exterior temp and AUC sensor which were replaced and errors cleared/fixed. There still seems to be something else shorting/drawing a load from the battery. Below are the codes currently present pulled from bimmerlink. Any ideas on what is going on or where to start looking? Any help is appreciated! It is my first BMW and I have been loving the car btw.

Integrated Chassis Management
2 errors
482609: SBS FUNCTION - LONGITUDINAL ACCELERATION SENSOR - FAULT TOLERANCE ON SIGNAL
480073: SBS FUNCTION - ACCELERATION - ADAPTIVE DATA FOR SENSOR TOLERANCE TO MAXIMUM VALUE
Front Electronic Module
1 error
804086: DRIVER KL15WUP: SHORT CIRCUIT BATTERY VOLTAGE
Instrument Panel Control Unit
1 error
B7F67B: COMBI: WAKE-UP LINE STATUS FAULTY (HARDWARE LINE)
Rear Electronic Module
5 errors
03010C: FH FAH, HALL ELEMENT A: SHORT CIRCUIT TO UBATT
03010D: FH FAH, HALL ELEMENT B: SHORT CIRCUIT TO UBATT
03010E: FH FAH, HALL ELEMENT A: LINE INTERRUPTION
03010F: FH FAH, HALL ELEMENT B: LINE INTERRUPTION
030120: FH FAH: SYSTEM IS NOT NORMALIZED

[328 Power 04]

Have you replaced the battery? If it's original, it should be replaced with a similar battery like the original, and registered the replacement.

So far you don't know if those errors are old stored errors or not. I would clear and then read again.

[Atunker]

Ah, I did forget to mention that the battery was replaced a few months ago by the previous owner. He bought a 95ah instead of a 90ah battery of the same battery type (AGM) but never registered it. I registered the battery using BimmerLink but registered it as a 90ah since there was no 95ah option within that coder. I figured this would be fine since bmw switched to 92ah and people seem to be registering them as 90ah and I hadn’t read of that causing any issues. I’m not sure if a 5ah difference makes a difference or not though.

As far as those codes go, I cleared all the codes after replacing the temp and AUC sensors and these were the codes that came back after clearing. So I assume they are all new/current codes.

[jclausen]

You need to do a charging system check and while doing that check for excess ac voltage and then check for parasitic electrical draws she the car is off

[Atunker]

You need to do a charging system check and while doing that check for excess ac voltage and then check for parasitic electrical draws she the car is off

After reading up from your recommendation I’ll attempt to see if there is any parasitic electrical draws using the “voltage across the fuses” method while the car is asleep in the coming days. I’ll report back with what I find. Thanks for all the suggestions thus far everyone.

[328 Power 04]

Has the car had any water entry?

[Atunker]

Has the car had any water entry?

Not that I’m aware of but I’m the 4th owner. Where would you recommend looking to determine if there has been any water damage?

[328 Power 04]

The wakeup line comes from the Front Electronics Module (passenger side footwell, below the A pillar, on the sidewall) and goes to a splice, which sends the wakeup voltage (a simple +12V) to many other modules.

Newtis is very good for wiring diagrams and where it all goes to https://www.newtis.info/tisv2/a/en/
You can also find where these longitudinal sensors and such are located.

You should also take a look at the Rear Electronics Module and the rear fusebox. Both in the trunk.


It's just a suspicion, it may not be that at all.

[Atunker]

Ok, after checking if there is any current drawing from the fuse boxes after the car goes to sleep, I found a significant draw on the instrument panel fuse. This would seem to match up with the “WAKE-UP LINE STATUS FAULTY” code associated with the instrument cluster previously posted in this thread. I guess from here I’ll try and get to that front electronic module and instrument panel control unit and see if I can find anything abnormal. Any ideas on how to test if these modules are bad?

[Marc repair]

and did you find something? Problem solved? I have the same problem. Start knob stays active all the time.