[xpat]

Hi, my problem is that the Radio turns on and works when the temperature is in the range of 60 to 70 degrees, and it automatically starts and stops after some time, usually under 30 minutes. it doesn't work frequently but rarely does. I am not sure what could cause this. 2009 bmw 328i xdrive sedan auto thank you. where can I start to troubleshoot this issue. appreciate your help. generally the radio doesn't turn on and no power at all. But it starts automatically, when the temperature is around 60F degrees.

[ctuna]

First thing is your car battery any good.
Because the IBS system will start to shut stuff down if
the battery is weak.

https://www.e92n55.com/wp-content/up...us-systems.pdf

If you are sitting in your car listening to music it will time out also after a certain number of minutes.

[ShadyOrb]

Having the same issue. Radio worked fine, then I replaced my dying battery with a brand new one. Now the radio no longer shows a display. The interior lighting works on the radio, but there is no power to the display.

I checked all the fuses, including the one on back of the radio. I also confirmed the radio has 12v constant (red/green wire).

At first I thought I may have coded something wrong, but I've tried multiple times and I'm not having any luck.

[ShadyOrb]

If anyone is having the same issue I've found the fix for it. This had me scratching my head for months, but I learned a lot.

Here's a little backstory of my troubleshooting. I find this helps when you're looking for a solution yourself.

I purchased a new radio but it was unfortunately heavily damaged in shipping, it powered on but the radio antenna snapped off the board, so I wasn't happy keeping it.

I couldn't understand how my previous radio worked completely fine, but after unplugging the battery it just died completely. All the fuses checked out, but no power to the display, and no sound from the CD drive when pressing eject.

After looking at every thread on the internet, and every video I came up with nothing. I assumed some freak glitch happened that just fried the radio or corrupted the on-board memory.

Fast-forward a few days and I decided to learn the BMW Standard Tools software suite, and tried diagnosing the radio myself. In INPA I noticed the radio still showed up as a module under the User Information Field.

I then opened up NCSExpert and tried reading the memory, and it worked...
Opened up the trace file and everything there seemed correct. If the radio is fried, and gets no power how can I read and write memory to it?

Then I figured it out.

Here's hopefully the definitive way to fix a broken radio. I listed each method from easiest to most advanced.

- Disconnect the negative terminal on the battery, wait 30 mins, and reconnect. Check to see if the radio is functioning again.

- Make sure all of the fuses in your fuse box are working. Not just the ones related to the radio. Visually inspecting fuses can be unreliable, make sure to test continuity with a multi-meter. Replaced any blown fuses, and hopefully that fixes your issue.

- Press the eject button, can you hear the CD tray functioning? If you never noticed it before, like me, it's a pretty obvious noise. If you can, and there is no display there is most likely a physical hardware issue with the head unit. Continue trying each step, if nothing works jump to the hardware repair section.

- What finally fixed this issue for me was TRANSPORT MODE. I'm assuming here, but I think it's enabled when the cars were being delivered to reduce battery drain, and then disabled by the dealerships. I guess when the battery got reconnected some weird glitch did happen, and the radio got stuck in transport mode. See transport mode section.

TRANSPORT MODE
Simply load up INPA, and turn off transport mode. I don't have INPA with me right now, so I cannot give exact steps, but it's very simple. Give it a Google.

HARDWARE REPAIR
If you can hear your CD player functioning, but there is no display on the head unit your radio likely has a hardware defect. But thankfully it's most likely pretty simple to fix.

Here's how:

- Completely disassemble the radio and removed the main board. You can just disconnect the display portion's ribbon cable and set it aside.

- Once the main board is removed from the shell flip it over, you're going to have to look for very tiny white text on the board, and you should find a label Q821, near that area you'll see these tiny SMD fuses. The fuses are labeled with a small white 'M' or 'F'. Test each one for continuity, if one does not have continuity. Drop a ball of solder on top of the fuse, bridging the two contact points. You could also replace the fuse, but I can't help you with that part. There is also another point Q823 check there too.

Hopefully after either replacing one of these blown fuses, or bridging the connection your radio will function as normal again.

For more information on this hardware fix, here's where I got it:
- https://www.digital-kaos.co.uk/forum...oesn-t-turn-on
-

If you're not comfortable with the hardware repair, or it doesn't end up working. You're going to have to replace your head unit. Keep in mind that the new unit will most likely require coding, so do your research.

If anyone has any questions, or would like me to disable transport mode for them. Feel free to PM me, or reply to this thread and I'll do my best to help you out.

[GSB]

Strange. Thanks for sharing your experience!

[drillsir]

Originally Posted by Bmwguyosk

Edit: I have solved/fixed the problem

The problem of having no power to the fuses that power the radio-
The fix for me was - if replacing the fuse box to a new one,
Dont forget these 2 fuses. (Pic in attachment) zoom in!
Black lookin fuses deep in the fuse box.




Im doing some diagnostic on my brothers 328xi 2009 e90
Car had no power what so ever.
Replaced ground strap under front wheel(was completely broken)
Replaced b+ wire and fuse box.

Car works mostly

Now the radio wont turn on. Most fuses are 12v+, but no 12v to the fuses that supply to the HU (tested connector behind HU and fuses) im getting 353mV back there

Tried with and without Ibs plugged in

everything else is working

Still no luck. Whats next in line to the HU power connector, is it directly to the fuse 14?
The fuses are not showing 12v

Thanks ahead of time if you take the time to read this^^

Oh, i also have Ista + , inpa, multimeters, and so on.

This was exactly my problem. I replaced the power distribution box and absolutely forgot to transfer over the two electrical shunts that feed accessory power from the relay to the bus bars inside the PDB that power the radio and some other accessories. Many thanks for this post!