Hi all. Newbie to the forum. I have a 2018 X3 M sport 2.0D I have set all doors and tailgate to unlock when the engine is turned off. Sometimes they do unlock and on the odd occasion they remain locked. Has anyone experienced something like this before. Thanks in advance. 

 

Welcome Paul. 
is it all the doors stay locked at the same time or a random one?

my Porsche’s rear right started doing it and it turned out to be the door actuator. 
 

if it’s all at the same time every time, I would look at the relays as it’s giving a signal to all doors. Random 1 door will be getting the signal but failing to actuate

Thanks for the reply. It's passenger and rear doors and tailgate, but only occasionally. I'll look at a replacement actuator and see if that solves the issue. 👍

An update to the intermittent fault. The issue with the passenger door, rear doors and tailgate not unlocking only happens if the radio doesn't turn off when the engine is off and the driver's door is opened!! Very odd. All settings in the idrive are for the radio to turn off and all doors and tailgate to unlock when the engine is turned off and driver'sdoor is opened. Anyone out there who has experienced anything like this? Thanks.

Hi Paul

I would from that description suspect a Footwell Module or Junction Box fault a diagnostic scan with a good BMW capable system should confirm (Best is BMW INPA/ISTA) 

Dave

Thanks Dave. I have recently had a diagnostic test on the vehicle as there was a fault with the tcu battery, which needed replacing. Would the door unlocking fault have shown during this or not due to it being an intermittent issue? Thanks again for your help

Hi Paul

As the fault is intermittent it always a mission to track down, INPA/ISTA will show faults present and faults not present but recorded in the history. So if INPA/ISTA was used I would have expected the fault to be seen

Many garages just clear faults then see what comes back (not helpful at times) The fact that your radio seems to be linked to the fault occurrence makes me think the issue is with either the Footwell Module or Junction Box as these modules are the ones that link the two systems (Radio is on the MOST Bus circuit Doors are I believe K-Can)

Dave

Thanks again Dave. The diagnostic check was done at a main dealership so I assume it will be as you suggested. I'll call in at my local garage in the morning and run through the things you suspect could be the cause. I appreciate your help with this.

Morning Paul

I would expect a Dealership to understand the Diagnostic programme, however as they say "never Assume" 

As an old (very) engineer I was always taught to treat a fault as a symptom rather than the actual cause. Sadly modern thinking and diagnostics have lead to a part swapping culture quite often at the Clients cost. 

I would start by getting a really good electrical contact cleaner, then first disconnect the battery unplug the Footwell module (also called FRM) and clean and check all the plugs and pins, if all good put it back and repeat with the Junction box (JBE) if all good reconnect the battery carry out a diagnostic. Record any faults then clear the active faults if there are any. The screen shot below shows the cars control unit tree not shown is the JBE the Yellow and Blue lines at the top come from there, the JBE manages the 2 main communication lines. On the left 3 down is the CAS (Comfort Access System) second line at the bottom FRM (Footwell Module) third blue line is the Most bus Infotainment 

In the screen shot you can see the IHKA in yellow (investigation shows Aux Water Pump) far right the DDE is yellow as 2 glow plugs are not working.

The control tree for your car will depend on the original build sheet for equipment but at least you can see how things are linked. As your issue is intermittent my thought process is more loose or corroded pin on one of the connection plugs on either the JBE (on the side of the fuse box) or the Footwell module

Hope this helps

Dave

Thanks Dave. That's great detailed information. You're right, we do tend to replace rather than mend (if possible) and I'm all for saving a few pennies!! This will keep me busy next week. 

ATB