bmw z4 28i m sport 2015 model cant get into the boot no battery inside

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robertlancaster1094

Member
My bmw z4 28i m sport 2015 wouldn't start and was completely flat battery so i called out breakdown recover and he managed to jump the car using the terminals found under the bonnet with jump leads and this gave us access to the battery in the boot and it turned out the boot was flooded with water where the battery and roof motor is, the roof motor is damaged so he disconnected that and also took the battery out as we drained out all the water and let it dry, as the battery is a sealed unit he said i can potentially salvage it if i go charge it up so i took it inside and before he left i asked is it ok if i close the car boot and will i be able to use the terminals to power the car to open the boot and he said yes, i then charged the battery and went back a few days later and i am unable to jump the car with the terminals under the bonnet so i asked a local mechanic and he told me no the terminals wont work because without the battery it has no full circuit so the car wont be jumped , he tried to plug in diagnostics to see if that can power the car and said power is getting to the car but there isnt enough juice to get the boot open to put the battery back in , there is no manual access to the boot at all ive looked all over and looked it up online and it tells me to use the bonnet terminals but i cant cos i have no battery and bmw doesnt even acknowledge that this problem is possible so now my car is just sitting outside gathering dust and i cant access the boot at all the only thing i can get to is the drivers door as it has a manual lock on it. does anyone have idea what i can do to simply get into my boot to plug a battery in and power the car , i dont think the car has any issues wrong with it other than this water leak which i read is a common problem and ive got a cover on it now till i find out the cause but wont be able to cos i just cant access the car, very poor design by bmw i dont understand why they cant just add a manual lock when the drivers door has one.


UPDATE :The water leak caused the electric box in the boot that all the wires plug into to corrode which resulted in very low voltage it was a cheap part but just a hassle to get into i got bmw specialists who had to spend time doing some research on the wiring diagram in order to get in i believe they may have done the fuse box method i was recommended but didn't feel confident doing myself but all is fixed now apart from the roof motor that needs replacing in order to get the roof up and down and also find the cause of the water leaks which i think is a common issue, they did open some plug holes in the boot for me to prevent any water building up in future if it happens to get in but other than that ive purchases a good water proof car cover that i always have on it if i am not driving
 
I had this problem when I foolishly took my battery out to bench charge it and shut the boot. I opened the ski hatch and pushed the back bit through into the boot giving me access. Then I just about managed to put a live and earth on the terminals and opened the boot with the key. I guess it depends what kind of hatch you have. Was a bit of a panic for a while.
 
i dont have a ski hatch unfortunately, i live in the uk and dont think they make them for z4 here and i dont have a button in the footwell either that some people have that gives boot access my care is just 100% reliant on power to get into the boot
 
i dont have a ski hatch unfortunately, i live in the uk and dont think they make them for z4 here and i dont have a button in the footwell either that some people have that gives boot access my care is just 100% reliant on power to get into the boot
 
I’m sure there’s a way to do it by linking something in the fuse box in the car but I assume that will only work with the battery in place……..This is a very bad design by BMW.
 
The key in the fob will open the door..

Once you open the door you pop the bonnet..

You put a chunky well charged battery via jumpers to the engine bay charge point. You put a decent charger across the combo and let it gently simmer.

Then you release the boot.
 
If for some reason the fob won’t open the boot you can use the pin 12 method in the fuse box, see the link below
https://z4-forum.com/forum/viewtopic.php?p=1853940&hilit=trouble%2C+two#p1853940
 
i got a mechanic to try everything on it today with the terminals under the bonnet etc and he said im gonna have to contact an auto electrician , also i thought of another idea is it safe for me to cut out the metal panel behind the seats and installing my own ski hatch for boot access
 
robertlancaster1094 said:
i got a mechanic to try everything on it today with the terminals under the bonnet etc and he said im gonna have to contact an auto electrician , also i thought of another idea is it safe for me to cut out the metal panel behind the seats and installing my own ski hatch for boot access
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The car will have a plastic blanking plate where the ski hatch goes..no need for cutting any steel.
 
Can you gain access to the terminals under the bonnet and the cabin of the car?
A few years ago I was working on mine (replacing the seats to sport ones) with the roof down with the negative disconnected from the battery..I accidentally shut the boot lid.... no power! :o So thinking quickly as I could feel rain in the air and before total panic set in, I tried connecting the terminals under the bonnet by jump leads to one of my other cars , then started the other car up. From memory I either pressed the central locking button on the dash twice or pressed the boot release button on the fob and there was just enough juice going through the system to open it (not to start the car). Good luck, I have a ski hatch and there's no way you'd reach the battery... maybe with a toddler fitted with a miners lamp and an aptitude for car electronics. :thumbsdown:
 
the terminals under the car dont power the car enough the boot is a tiny bit open but not completely disengaged and i cant give it anymore juice and the battery isnt inside the car
 
robertlancaster1094 said:
the terminals under the car dont power the car enough the boot is a tiny bit open but not completely disengaged and i cant give it anymore juice and the battery isnt inside the car
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What battery are you using to do this..I assume it’s a new fully charged one ?
 
I’m confused is the boot open or closed ?….yiu say it’s ‘slightly’ open..do you have a picture ?
 
i will add pictures to this tomorrow as im about to sleep but the terminals basically made the boot pop up a bit but i can only stick my hands under it and when i look under its just sealed a mechanic told me one of the locks released but another one didnt or something i domt know how it all works but the car wont power up enough to do anything now its like it used up all its juice. also how risky is the fusebox method? i had a look at that and thinking of just trying that
 
Trying to think a little out of the box, have you tried powering from under the bonnet and putting the key in with ignition on and then typing to open the boot?
I haven’t tried the fuse box 12 pin method but can’t see any reason why it wouldn’t work.
 
i have tried powering under the bonnet then putting the key ignition in and nothing happened but i havnt tried opening the boot with the key in the ignition its worth a try
 
If you know someone with a proper scanner like ISTA or Bimmergeeks ProTool (for android ), the boot can be triggered easily. Otherwise do the pin 12 method. You will just have to crawl around under the glove box. Someone did an excellent tutorial on the pin 12 method
 
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