94 740IL-Mute function interupts CD and FM every 5 seconds

Unable to pinpoint why the mute function interupts listening while in CD and FM modes only. Weatherband, AM and Cassette do not have the same problem. I understand the Phone can interupt radio function when an incoming call is detected. But the phone is not currently installed. BMW has suggested the hands free microphone for the phone has malfunctioned (currently trying to isolate this). Can only use 40% volume. Any suggestions????

My phone isn't hooked up so I was wondering, how do you know it's the phone's mute function causing the problem? Does the display read "MUTE" or something? Also, does this happen every 5 seconds like clockwork or did you just mean that it happens at random intervals with a 5 second average?

If it's the phone: In the trunk, behind the trim panel that has the ski bag, there's some phone equipment. You might try to climb in there and disconnect it and see what happens. I think the amplifier is in the same location so make sure it's the phone you disconnect.

Also, maybe it's your amplifier that's malfunctioning. FM radio and the CD player will send signals to be amplified at higher frequencies than the other equipment can produce. Maybe the amp has a problem such that when these frequencies are recieved it cuts out momemtarily but amplifies the lower frequencies OK. Maybe.

My phone isn't hooked up so I was wondering, how do you know it's the phone's mute function causing the problem? Does the display read "MUTE" or something? Also, does this happen every 5 seconds like clockwork or did you just mean that it happens at random intervals with a 5 second average?

If it's the phone: In the trunk, behind the trim panel that has the ski bag, there's some phone equipment. You might try to climb in there and disconnect it and see what happens. I think the amplifier is in the same location so make sure it's the phone you disconnect.

Also, maybe it's your amplifier that's malfunctioning. FM radio and the CD player will send signals to be amplified at higher frequencies than the other equipment can produce. Maybe the amp has a problem such that when these frequencies are recieved it cuts out momemtarily but amplifies the lower frequencies OK. Maybe.


Above 40% volume the radio display shows "MUTE" and it just happens frequently, random intervals.

Thanks for your suggestion about the phone equipment/amp in the trunk, will check this out. Are you aware of a good source for electrical schematics? This might be helpful.

I have the schematics, gibbz80, but I'll need your mailing address because they don't email very well. Send it me at [email protected].