In this article I describe the electronic issue(s) that I am having on a 2010 BMW 750i
Specs of 2009 F01 Chassis:
Increased Battery Discharge and Full Electronic Failure
This car is second hand and has always had an electronics issue whereby when I enter the car, it reports that the electronic systems were shut off due to "Increased battery discharge" while stopped ("Battery discharging while stopped - Electrical devices were temporarily switched off"). Since I did not know how old the battery was, I had the battery changed but this did not resolve the issue. I was able to drive the car and have been for several months while I continue to troubleshoot the battery discharge issue. I took the car to a specialty shop where they did transmission pan/filter and fluid replacement, front and rear diff oil replacement, a coil replacement, oil and filter changes but they could never figure out what the problem is with the electrical system. The reason for including the battery discharge issue here is that this issue may be related to my current issue (which is now a repeat issue). The car is currently demonstrating a "Full Electronic Failure" where the car reports that many systems are not functioning.
Here is what the car shows as trouble codes and as a result is not drivable.
My suspicion is a short in the comfort access handles (or at least one of them) is potentially the cause for both these issues.
Battery Discharge Troubleshooting
I have taken the easy steps of ensuring that there are no USB devices, etc. plugged in the car that could be draining the battery while stopped. I also changed the battery and tightened the battery terminals. No improvement. This is the extent of the troubleshooting to date. In the meantime, I had a "Full Electronic Failure" and am now into my second one. I now suspect that these may be related issues. I suspect that the CAS (Comfort Access System) is the root cause of my "Full Electronic Failure" and may be contributing to my battery drain issue?
Battery Check
- Check to see if you need to charge the battery - charge if required
- Battery Voltage and State of Charge
12.66V . . . . . . . . . . 100%
12.45V . . . . . . . . . . 75%
12.24V . . . . . . . . . . 50%
12.06V . . . . . . . . . . 25%
11.89V . . . . . . . . . . 0% - Here is a good youtube video on the Discharge issue and how to check your battery and the ground terminal sensor located on the negative battery terminal at the rear of the vehicle.
- Note: Battery should be above 12V when vehicle off and on.
- Takes about 48hrs to trickle charge a battery at 2Amps
- https://m.youtube.com/watch?v=avqULg055WM
- Here is a site that shows how to code a new battery
- Battery Voltage and State of Charge
Fixing the First Full Electronic Failure
The complete system failure has happened previously and when I checked my fuses, I found that fuse #2 in the front fuse box behind the glove box had failed. Once I replaced the fuse and cleared all codes, the car went back to normal.
Here is a map of the fuses for the front fuse box behind the glove box
I believe that there is an intermittent short and/or failure in the CAS entry system driven by one of the door handles. I also suspect that wet weather rain/snow or car washing can exacerbate the issue.
Q4 2022-2023 Update
I have not found the root cause for the battery discharge, however now the car is once again (for the second time) having the "Full Electronic failure" issue and sure enough when I investigated, fuse #2 was blown again. I changed it, however this time, I cannot get the car to reset and start up again. I suspect that I have a faulty CAS (door handle).
Fuse #2 is shared between the Comfort Access System (CAS) and the ABS Module. I am going to assume that it is a CAS - door handle that is the cause for the failure (i.e. affecting the CAS - causing everything to go haywire).
The investigation continues - but for now the car is grounded in place as it cannot be driven....Next step is to remove all the handles, replace fuse #2 (again) and see if the car returns operational.
Problem: Fuse #2 (in the glovebox) has most likely been blown due to a short in the CAS (Comfort Access System). Many of the vehicle's systems that are not working are dependent on this fuse. Hopefully it has nothing to do with the ABS unit as that would be a very expensive repair.
CAS Troubleshooting Strategy:
Remove all 4 door handles and disconnect the electrics.
- Using a "T15 hex" screwdriver go thru the access port on the side of each door which is covered by a rubber grommet. Unscrew the bolt to release the door handle and remove (note: the bolt is held in place - so no chance of loosing the hex bolt so undo it all the way).
- Disconnect both the 4 pin (CAS) and 2 pin (door light) connectors on all four handles. Use a small flat head screwdriver to ease off the connectors. This covers a short in either the CAS and/or the entry lights.
- Cover the connectors with some electrical tape to try to keep moisture out.
- Add a pull sting between the connectors in case future retrieval is required
- Replace the door handles and rubber grommets.
- Check and/or replace fuse #2 and see if system returns operational.
If my theory is correct, I may just leave the CAS door handles all disconnected and see if my battery discharge issue also goes away. I then can address the handles individually if I want to return the CAS and/or lights to be functional for each door.
Success
So far so good! I executed on my CAS troubleshooting and the car is now no longer throwing any codes and is operational. Fuse #2 was blown (again) so I replaced it. This fuse box is tucked way up behind the glove box but with a little effort you can remove and replace the fuse.
Fingers crossed - lets see how log this lasts and whether we have a permanent root cause for the "Full Electrical Failure" and also whether we solved the "Increased battery discharge" issue.
Success Again
Success - even thou the battery was only charged to about 85% (12.4V), I decided to test drive the car. It had been sitting for a while so I was not sure how well it would drive but it drove as well as it did before the "Full Electronic Failure". It is too soon to tell if this was the root cause for the battery leakage - but time will tell, For now, I am happy that the car is back functional and at least back working as it was prior to this latest round of electrical issues.
Replacing and RE-coding the Battery
Now that I have fixed my issues - it appears that the battery is gone on the car so I need to get a replacement and code in the new battery.
I cannot get a reliable copy of ITSA-P with Reingold so grabbed the Bimmergeeks tools (INPA, Tool32, etc) in an attempt to get this done. I also purchased a ENet cable for the job.
ENET Cable
I was able to install Bimmergeeks tools but had to copy over some of the english libraries to try to get INPA connected and running smoothly.
In my case I am using a ENET cable so had to configure my TCP/IP LAN port to a static IP of: 169.254.1.1 (subnet will automatically be 255.255.0.0 and DNS, etc can be blank). An important step is to get a copy of INPA from someone using ENET of install the default application and make sure to specify ENET as you communications protocol. I did the latter - but then had to copy many of the config files fro another installation to get things running smoothly.
Removing the battery
- Use a 8mm socket for the negative and an 10mm for the positive terminals and yank it out.
- Make sure to take note of the Specs on the old battery as well as the specs on the new battery as you may need to code in the battery details.
- AmpHours and Cold Cranking Amps (CCA) [Ideally around 110 Amp Hours and 920 CCA]
- Using INPA - the power module may be in the Chassis, CAS or DME
Here is the Battery
Programming Using INPA and Tool32
I loaded Bimmergeeks tools (INPA and Tool32) to get the status of the modules in the car. In my case I needed to find out which modules I am using in the 2010 F01 in order to use them in Tools32. Here is what the information tab in INPA provided:
Take note of the SGBD Column - those names correspond to the Program files that you can load to manipulate each module. The most important for my 2009 F01 is the module MSD85L6. In this module you will find the program that you can use to register the new battery. Near the bottom of the list is a program called "steuern_batterietausch_registrieren" - then run Job Einmal Ausfuhren and wait for the "okay"
Using NCSExper.exe to Change Battery Spec:
Now that we have the battery replaced we may need to tell the Intelligent Charging Sensor (IBS) system what size battery did we put in if it differs from the previous battery specifications. In our case it will be a 92ah battery - so the closest setting is 90ah. However, the F series chassis cannot be programmed using NCSExper. Luckily the OEM battery was a 92ah AGM battery so this will be like-for-like replacement and therefore just needs the registration to indicate that there is a new battery.
ESYS:
To use ESYS on my old laptop, I needed to get the .NET framework up to 4.6.1 (from 3.5.1 SP2). So to do this I had to use the offline loaders for 4.0, ... up to 4.6.1. The challenge is that this laptop was being used to run the Bimmergeeks tools on XP. Unfortunately the lite version of ESYS utilizes a "launcher" that requires a later version of the .NET framework (4.6.1). XP does not support .NET 4.6.1. So you need to run it on a new OS (run in compatibility mode).
Ordered a Bluetooth ODB Dongle:
I finally broke down and purchased a Bluetooth ODB transmitter. The best (yet pricey >$200) device is the OBDLink MX+. It works with iOS, Android or Windows and is a professional-grade OBD2 Scanner and vehicle performance monitor. I can use this device if I end up purchasing a scanning app like BimmerLink?
I also purchased the Bimmerlink app for $49.99 to try with the dongle. Works great and I highly recommend this combination!
New Battery
Since I have an aftermarket battery with a 5 year warranty - I took it back and had it tested and confirmed that the battery had a dead cell!! Time to get a new battery under warranty as it was purchased under 3 years ago. I checked and the shop only specs and sell the 92Ah battery - So going to code in that battery for now. I would love to have upgraded to the 105Ah battery as per the new spec from 2013.
Installed the new battery and the car is now running reliably!
Junction Box - AUC Sensor Error
With my scanner, I can now troubleshoot any persistent errors. One error is located in the Junction Box module with the AUC Sensor.
I sourced a new sensor from China and it showed up in about 2 weeks (11 days). Installed the new sensor and the error is now cleared. The new sensor is identical down to the BMW logo (which was pixelated - the only difference).
Here is the original defective sensor:
Time to Reconnect CAS Door Handles
With the new battery installed, it is time to reinstall the Comfort Access System (CAS) door handles and test. With the handles re-installed - everything seems to be working fine for now. I am now done to 7 errors.
7 Remaining Errors:
Here are the 7 remaining issues after I managed to successfully re-calibrate the sunroof, seats and the windows.
Allround View Cameras - 2 errors
It appears that my side-view cameras are not connected properly or water damaged. Will need to remove the wheelwell shrouds to investigate.
Driver's Side Footwell Module - 2 errors
Seat Module - Driver - Rear - 1 error
Note sure if the seat needs to re-calibrated or not. Here is a youtube video on how to re-calibrate.
Motor Electronics - 1 error
Central Gateway Module - 1 error
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