[mweisdorfer]

I know the answer is to run the power line directly to the battery.

However, if anyone knows what empty fuse that I have in my fuse box, which gives continuously power 24/7, it would be greatly appreciated.

I have an 07 335i with a 01/07 build date. BMW put in a revised power box from 03/07 going forward. So, e90's built from 2006 through 02/07 got one fuse box, and BMW installed a revised fuse box in cars built 03/07 going forward. IDK, if at some point, BMW made additional revisions of the fuse box from 03/07 to 2012.

I have attached a pic of my fuse box, a pic of a pre-03/07 fuse box, that has all the fuses numbered, and pic(s) of the legend, which tells you what each fuse is used for based on the number.

I highlighted the fuses I am not using (ones that are vacant). I circled in pencil ones that have fuses in them, but I don't have that option on my car.

So, basically there are 22 fuses to chose from.

Can anyone give me any insight as to which fuse, open or one of the 4 that have a fuse in them, which I don't have that option, that provides constant power 24/7??????

[EndOfAnEra]

Go buy a digital multimeter. You’ll be glad you did.

[mweisdorfer]

Originally Posted by EndOfAnEra

Go buy a digital multimeter. You'll be glad you did.

I forgot to mention that most of the fuses will register as hot. However, a lot of them will not give power after around 15 min to an hour. Multi-meter is helpful but then you have to let it sit hooked up to the fuse for an hour and see if you still get a reading.

You can't open the car door once you start the test....

Yep, you could have the windows down. It would be my luck that the very last one I tried worked !!! 22 hours later!!!

[mweisdorfer]

If I am looking at this correctly, no 42 that goes to the trailer module is a constant 24/7 twelve V source of power....