Alexowen

Hi guys,

I apologize in advance for such a long post, but I’m in desperate need of help. I’ve looked over this site for a few years now and you guys have been very helpful in solving many simple problems with my 535i and I thank you all for your contributions.
I’ve looked around the forums and couldn’t find a similar situation so I apologize if I’m asking something that’s already been answered.
I’ve been having a few issues with my ’08 535i that have progressively gotten worse as time goes on. I purchased the car in 2011 and everything worked perfectly. About a year later, sudden electrical gremlins started popping up. Here are the issues in the order they happened:

Bluetooth stopped working but the option is still in the utility menu grayed out.

Voice command (button on the steering wheel) does nothing.

The speakers started to ‘pop & crackle’ and the sound also would cut in and out like a skipping CD but it happens with the radio too.

The USB/AUX ports in the console stopped working and have no power going to them nor will the aux jack play audio when a device is connected directly to the jack. The AUX is also grayed out in the CCC menu.

The keyless start stopped working (with both keys). The car won’t respond or start unless the fob is pushed in the ignition port. I replaced he fob batteries with no luck.

Comfort access stopped working on all doors. The car must be unlocked with remote or the manual key in the remote.

I’ve tried to figure out what the deal is but have hit a dead end every time. I’ve replace and had coded to CCC head unit. I tried the replace the TCU module in the truck but the online coder said his program couldn’t communicate with the TCU so I sent that one back and got a new TCU but the same problem happened. I’ve tried to find a diagram of all of the modules in the MOST system in order so I can see what’s before the TCU that may be preventing the coders program from communicating with it.

I’ve been trying to fix these issues for over a year and it has become extremely frustrating. Thanks for your time and input.

cmyachtie

How old is your battery?
If never renewed yet go get a new battery.
If your battery is good, looks like you need dealer to reinstall software whole car,

Alexowen

Thanks for your reply.
I replaced the battery less than two months ago and the whole system has been reset (not by a dealer) about a week ago. Nothing has changed. Over the past six months, I've had two online coding companies and one indie mechanic try to fix it with flashing the whole system but it still has the same problems. I've tried replacing the TCU, twice, but nobody can communicate with it on their computer. I've tried replacing the MULF module under the spare tire but still no luck. I'm stumped.