Hi everyone!

I've lost the subs in the rear shelf. I get no sound out of them unless I turn up the volume really high and only then I get some pathetic low-volume sound out of them. Is it the amp?

Thanks in advance!

The amp is one of those things that are on the "bound to fail" list. I had a bad front and took the door apart thinking it was the speaker (waste of time)
It is strange that both left and right rear would go at the same time, but it makes sense, and one could have been out and you did not notice. Everything including the fader runs thru this amp.
These are seven channel amps (with 11 speakers), and there are capacitors that leak and go bad, sometimes blowing up the circuit board. MB sells new ones, $900, some dealers have rebuilts $600, I had the dealer plug in a rebuilt and it did not work properly. I told them to take it back, nice parts guy (you know no returns on electrical) policy. They directed me to their local rebuilder, who repaired mine for $600 including the smaller amp with a one year warranty.
If you look at the BECKER web page they offer a rebuild service, and a listing of authorized repair facilities, which might be more convenient.
The amp(S) are located above the rear wheel on the passenger side, and are accessible after removing the liner in the wheelhouse area. If you have the CD it is a little more work, since it has to be removed. Pull the center out of the rivets, pull the base and carefully pull out the liner, the tail light come out easily by sliding the lock and removing the connector.
You can reverse the right and left coming out of the tuner just for the fun of it to see if things change (the tuner has the antenna lead and the cable that goes to the controlhead (front) that most people think is the radio. Both rear speakers, there are (4) are tied together as are the front door, the rear door are seperate, and the speakers on the dash are for the cell phone, and the one behind the mirror is a fill in.
While you are back there the other "fail" item is the closing pump, not to be confused with the locking pump (under the seat), this pulls in the doors, some other items, and trunk lid. This will be another discussion

Thanks so much for the detailed info. I will go to Becker to find somebody to fix the amps then. The pump you're talking about, closing assist for the doors and the trunk, I KNOW I need a new one since periodically I need to reset it to bring it back to life (either trunk or rear doors lose assist function). Are you saying that closing assist pump IS NOT the one under the rear seat? I always thought it was the same thing.

I hope the info was some help, there are two vacum pumps, the one under the seat is used to lock and unlock the doors, backup assist, trunk lid grip, headrests on some versions, orthopedic seats, and manifold vacum-assist for hvac. The other over the rear wheel controls the "pull-in" of the doors and lid. The bulletin to the dealers modifies the handle to pull in when the lid closes you will notice if there is a delay after the trunk closes the handle pulls in. At least on my 92, I was a veteran of the fuse pull game.

Where can I find these prices.My amp is going out and I have called $2400 at the MB dealer and I have a couple rebuilt for $800 each.....I would be happy to pay the $600


Warren
1992 300SD 166K
Columbus Ohio

Here's a place that will fix your Bose 7 channel amp for less than $500 and guarantee it for three years.
I have no experience with them; just found them on the web in anticipation of my own W140 amp going out..

http://www.bose-repair.com

Hope this helps, KenP

Yeah, I used those guys.

I used a cheaper place first (paid $300) and they put a bunch of incorrect crap in it and sent it back "sort of working".

The guys in FL said they could fix that guy's "bad repair". So I sent it to them. They charged me $170 and replaced a bunch of stuff. Has worked like a champ for 5 years.