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Registered
1993 500E
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142 Posts
Discussion Starter #1
I replaced the BOSE amp in my 1992 300SE. After fighting the MB soundproofing in the trunk I got the amp back in its place. Stereo worked fine, but I noticed that the close assist no longer worked on both driver side doors and the trunk. I think I may have "bumped" into the clump of red tubes that are the lines for the close assist.
Does anyone have a recommendation of steps to follow in trying to track down this problem? And, heaven forbid, if I cracked any of those red lines, are they difficult to replace/repair?

Thanks,
Eric
 

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92 500SEL to 01 E320T current 2014 lexus LS460
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3,886 Posts
To get the liner out remove all the plastic rivets, peal out from thr top, dont forget to remove the taillight. If you have a CD a little more work! Try resetting the pump by pulling fuse 9 or 10 I think for 10 seconds or so. Otherwise you will have to go in and see if you loosend the power connector or broke hose nipples.
 

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1993 500E
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142 Posts
Discussion Starter #3
Thanks Peter. I will tackle this afternoon. And thanks for telling me to remove the tail light...I wouldn' have thought to do that.

For resetting the pump by pulling the fuse, should I do that before trying anything else?
 

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w140 s300turbodiesel
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238 Posts
Remove tail light? Why is that? I removed the carpeting without having to remove the tail light at all
 

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92 500SEL to 01 E320T current 2014 lexus LS460
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3,886 Posts
On the earlier cars the liner is under the inner taillight housing, you can swing it out and disconnect the power connector on the 92/4 it slides out of the bracket can be removed (be gentle) and wont break while maneuvering the panel. I also would suggest that you take out the liner over the gas tank and rear speakers, it is much easier to get in there.
Yes I would do the reset trick first
 

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Registered
1993 500E
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142 Posts
Discussion Starter #6
I did the fuse reset and the driver side doors worked again for a couple of hours...then the driver door stopped working. The close assist for the trunk still doesn't work. Does that mean there is a leak somewhere?
 

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Registered
92 500SEL to 01 E320T current 2014 lexus LS460
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3,886 Posts
It probably means new pump, there is a tool called Mighty-Vac, that is used to check the elements to see if they leak. you plug it into the hose and draw a vacuum there is a guage to see if it leaks down.
The close pump uses "pressure" to draw in the door and then runs the other "vacuum" way to reset the diaphram. I would spend the $(fifty) to check lines
It is complicated, if it can not close a door after three tries it disables that circuit, there is also a pressure sensor. Do a search on "closing assist" it will keep you busy there is some good info out there.
 

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w140 s300turbodiesel
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238 Posts
the quickest way for you to fix this is as follows:

remove carpeting from the boot. reset the pump by pulling fuse 9 for 10 seconds. have someone close the doors while you sit in the boot and listen for any hissing noises. considering that the bose amp and the vacuum lines are relatively close (I think that the boot line actually goes behind the amp or thereabouts) there is a high probability of you having pinched one or more lines. in case of a leak it would then be a simple matter of applying some duck-tape to the offending line(s) or perhaps a drop of loctite. saves you the hassle of having to "re-tube" the car.
 

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Premium Member
1997 S600 (sold)
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4,660 Posts
You will hear an air leak. The pump moves a lot of air and develops a lot

of pressure. You'll just have to listen while the pump is operating to see if there is a leak. To get a good start on learning about the system, read my post on adjusting the shut-off pressure. Find it by searching the W140 forum by my username with the text "restoring function". You'll find my post "Restoring function to your closing assist pump. Adjusting the pump's shut-off pressure."

Also look for a thread by Posix on the closing assist pump. We had a long discussion, and he ultimately found his pump's problem lay with a leaking rubber diaphragm in the shut-off mechanism.

Keep us posted if you solve your problem. It's unlikely that you need a new pump. It's likely that your current pump is very repairable or simply needs a slight adjustment.

good luck,
Brett
 
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