My 94 E420 has the Bose system installed, along with the integrated cell phone. Occasionally, the volume on the stereo will perceptibly change so that the right channel is louder than the left. This happens even though I do not touch the volume control. It does not seem dependent on engine speed. It happens quite rarely, and without any real warning. I simply do not know what triggers it.

I do not plan on doing anything about it until it becomes more acute, but I am curious what could be causing the problem. I think these Bose systems have separate amplifiers for each speaker, so I guess that maybe the left front amp(s) is getting a little glitchy. I would hope that the head unit is not the problem.

Probably an intermittent loss of connection to one of your left speakers. Fade your stereo all the way to the front and drive around like that until you notice it again, or you think you should have noticed. If it doesn't happen, fade you stereo all the way to the rear and see if it happens then. This will help you figure out which speaker is giving you the trouble. Then, I would pull that speaker and check its connections.

I have a 95 E 420. Sometimes I lose only the left front speaker, sometimes I lose the left front and rear at the same time. If I turn the radio on and off, the offending speaker(s) begin working again. I have read other posts that describe the same behavior in these cars. Unfortunately, I also have no ides why it happens. I am going to buy a new system.

I just spoke with a Mercedes service advisor, who states that this particular Bose system has the automatic volume control, wherein the system is supposed to get louder as you increase speed. It sounds as if my sensor is somewhat out of whack, in that the volume changes irrespective of vehicle speed. He mentioned that it is possible to disconnect the automatic volume control so that the volume is constant regardless of vehicle speed. Does anyone know how to accomplish this? Does anyone know if the automatic volume control is separate from the radio so it can easily be replaced? Thanks.

volume has a mind of its own in my 94 s500. already replaced caps in bose amplifer. now volume cuts in and out or goes up and down on its own...any ideas would be great.

Hi, you have to cut or disconnect the wire A1 to exclude the auto volume control feature.
bye

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This is really interesting!!

Is this why the volume on my unit sometimes drops out completely?

The unit in question is the stock unit in a '95 E-320.

Thanks!

Does my unit have that automatic volume control?

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Current:
2014 VW Tiguan SEL 4Motion 43,000 miles.

2016 Hyundai Santa Fe Sport (wife's).

Past:
2006 Jetta TDI 135,970 miles. Sold Nov. '13.
1995 E-320 Special Edition. 220,200 miles. Sold Sept. '07.
1987 190-E 16 valve. 153,000 miles. Sold Feb. '06.
1980 300-D 225,000 miles. Donated to the National Kidney Foundation.
1980 240-D manual, 297,500 miles. Totaled by inattentive driver.