BMW Repair: no sound from speakers 99 E38, park distance control, parking sensors

Question
hi, I have an MK2 navigation system in my car and ever since I purchased the car (2 years ago) there has been a slight problem with the system. The system will not play sound from radio/cd/tape and will go into main menu and then back to what it was doing; this lasts for only a couple of seconds therefore it does not bother me and the frequency of which it would happen at each journey depended on how cold it is outside (the colder the more frequent). Lately though no sound will come out of the speakers no matter what I do and can last up to 5min with the screen not showing any problems. Sound will come up again if that "hikup" of the system happens as I explained before or just by itself after some time if the "hikup" does not occur. Parking sensors sound even if no sound is coming out of the navi. system.
Im not sure wheather its the amp, wire harness or the actual MK2 navi. Thanks.

Answer
Hi Michael,
First of all, the PDC (park distance control)) has no relation whatsoever to the NAV/Video/Audio system.
And there is always a delay in the various electronic systems at startup while everything boots up (of course there is a sequence in this, with I think the video/display booting up first, then the NAV, then the radio/cd).
The way you describe it, you have no problems with your video display or the NAV but have a problem with your audio.
But you failed to mention when the problem arises. Is it at start-up, or when the car has been running for awhile and you decide to use the radio/cd? If when the audio runs it runs continuously then the wirings/cables may not be at fault. If both radio and cd gives problems (they are separate assemblies), then it is the amplifier that is bad.
I suggest that you look for a good used amplifier (that would allow you to return it if it does not work),  then hook it up at the left rear trunk area.
Cheers!
Tino