Radio working... but no sound?
- Thread starter matthiasmilli
- Start date
Hm.. Yes. Nothing on the left side. Only that amp on the right side.
Bluetooth is definitely working as i've just paired a phone to the unit with no issues
Everything seems to be working - or 'look' like its working. I can flick between phone and radio, cd and usb - there is just no sound.
It's like i've just muted the speakers - but theres no mute button!
Bluetooth is definitely working as i've just paired a phone to the unit with no issues
Everything seems to be working - or 'look' like its working. I can flick between phone and radio, cd and usb - there is just no sound.
It's like i've just muted the speakers - but theres no mute button!
The whole of the BMW audio side is a minefield of different options, and working out what you've got is one hell of a headache without taking things apart.
So it looks like you've got the headunit with built-in Bluetooth and USB control, which is connected to the top hi-fi 677 system (14 speakers) via the MOST fibre optic.
So you could have a fuse for the amp blown, the amp blown itself, or maybe a faulty fibre optic wire or connection somewhere.
To test the MOST you need to unplug the MOST connector at each point (amp, headunit, maybe somewhere else) and see if there is the red light coming from one of the wires.
So it looks like you've got the headunit with built-in Bluetooth and USB control, which is connected to the top hi-fi 677 system (14 speakers) via the MOST fibre optic.
So you could have a fuse for the amp blown, the amp blown itself, or maybe a faulty fibre optic wire or connection somewhere.
To test the MOST you need to unplug the MOST connector at each point (amp, headunit, maybe somewhere else) and see if there is the red light coming from one of the wires.
Thanks - i'll check this in the morning...
Appreciate the help!
Appreciate the help!
Scottish Borders
Just asking a couple more questions before i start work on this tomorrow... (and forgive me, electrics isn't my thing!)
Earlier, it was stated that "if the amp isn't working then the MOST would be down!"
1) If the photo i posted earlier is the MOST unit (in the boot behind the drivers seat) - then where is the amplifier? Is there another one somewhere else?
2) Also, if the amplifier and the MOST are different units, and the amplifier is obviously just an amplifier - then what does the MOST do?
3) I've seen countless videos on Youtube where BMW's have this issue (radio on, but no sound) but none for the E89. Nearly all those videos use a female loop connector on a unit in the boot which once fitted, makes the sound come back on. Is this relevant for the E89? If so, where is the unit i'd fit this loop connector to?
Sorry if these are dumb questions - as i said, electrics aren't my thing!
Thanks in advance
Earlier, it was stated that "if the amp isn't working then the MOST would be down!"
1) If the photo i posted earlier is the MOST unit (in the boot behind the drivers seat) - then where is the amplifier? Is there another one somewhere else?
2) Also, if the amplifier and the MOST are different units, and the amplifier is obviously just an amplifier - then what does the MOST do?
3) I've seen countless videos on Youtube where BMW's have this issue (radio on, but no sound) but none for the E89. Nearly all those videos use a female loop connector on a unit in the boot which once fitted, makes the sound come back on. Is this relevant for the E89? If so, where is the unit i'd fit this loop connector to?
Sorry if these are dumb questions - as i said, electrics aren't my thing!
Thanks in advance
matthiasmilli said:
The box in the boot is the amp..the most cables run in a ring part of which is the head unit and the amp in the boot
MOST (Media Oriented Systems Transport) is a fibre optic based very high speed network technology…the 4 audio channels from the head unit travel down the fibre to the amp…it’s very fragile both physically and topologically..any break and /or any unit not retransmitting the signals and everything on the network goes down…it’s not the same as the fibre optic connector you may get from a tv to other consumer av units..
Great when it works..so good in fact bmw dropped it in later cars..
What he said 
In the video you posted, it showed a module that was connected to the fibre optic network (MOST). That can be one of a few different modules within the car that use the MOST. They can be any of the following....
Headunit
Amplifier
CD Changer
DVD Changer
DAB Receiver
TV Receiver
iPod Controller
MULF2 (Bluetooth calls)
Combox (Bluetooth calls/music)
I think the one in the video was either a DAB or TV receiver (they look the same). What they were doing was to bypass a faulty module. In your case though, if the amplfier has gone wrong you can't simply bypass it and the sound will come back as its the amplfier (ie; no amplfier = no sound anyway).
If the fuses look good, then you need to check the fibre optic network. As you have the panel out already then I'd suggest unclipping the fibre optic from the amp and see if you have one with a red light (ignition needs to be on). If so then move to the headunit and remove that (unclip the panel below it and you find 2 screws, remove these and release the headunit. I show this at 6:30 in this video...
https://youtu.be/VC9VFJBDFQM?si=Qz7Lm4Z_Z4TQyEtE )
Then remove the fibre optic plug from the radio quadlock connector and see if you get the red light.
If you have the red light at both the amp and radio ends then it means you've not got a break in the fibre optic. It probably means the amp is OK as well.
But let's not jump ahead, check that out first. Let's hope it's just a fuse
In the video you posted, it showed a module that was connected to the fibre optic network (MOST). That can be one of a few different modules within the car that use the MOST. They can be any of the following....
Headunit
Amplifier
CD Changer
DVD Changer
DAB Receiver
TV Receiver
iPod Controller
MULF2 (Bluetooth calls)
Combox (Bluetooth calls/music)
I think the one in the video was either a DAB or TV receiver (they look the same). What they were doing was to bypass a faulty module. In your case though, if the amplfier has gone wrong you can't simply bypass it and the sound will come back as its the amplfier (ie; no amplfier = no sound anyway).
If the fuses look good, then you need to check the fibre optic network. As you have the panel out already then I'd suggest unclipping the fibre optic from the amp and see if you have one with a red light (ignition needs to be on). If so then move to the headunit and remove that (unclip the panel below it and you find 2 screws, remove these and release the headunit. I show this at 6:30 in this video...
https://youtu.be/VC9VFJBDFQM?si=Qz7Lm4Z_Z4TQyEtE )
Then remove the fibre optic plug from the radio quadlock connector and see if you get the red light.
If you have the red light at both the amp and radio ends then it means you've not got a break in the fibre optic. It probably means the amp is OK as well.
But let's not jump ahead, check that out first. Let's hope it's just a fuse
Thanks for this - good information!
Just about to start work on it now and check the fuses
Can you tell me exactly where 104 is in the boot please?
Just want to make sure I know what I’m looking for
Also, do you know what size fuse it is?
There’s no map like the one in the glove box!
Many thanks
Just about to start work on it now and check the fuses
Can you tell me exactly where 104 is in the boot please?
Just want to make sure I know what I’m looking for
Also, do you know what size fuse it is?
There’s no map like the one in the glove box!
Many thanks
Thanks - I've swapped over number 69 and still the same issue
Now to hunt for 104
I assume its in the red block of wires next to the battery?
Now to hunt for 104
I assume its in the red block of wires next to the battery?
Hmm well i've found the red block of wires but can't see any fuses!?