I have a First Year W140 S class with Door Closing Aid. I had some problems with my closing aid but it is now fixed and working properly. I bought a plug and play circuit and in minutes my doors are working perfectly again. Cost was cheap. I would tell you where you can get this circuit to help those with similar problems, but I do not want to advertise or be accused of advertising in the room and have this post pulled. I only want to help those that have closing aid problems as I had. I dreamed of a day some one would come up with a fix for this problem.. And some one has...

The ONLY easy fix on failing closing aid systems on the S-class is usually a brand new pump, and even that does not guarantee a permanent fix, as some brand new pumps tend to fail suddenly again.

Most of the fixes I have seen advertised are usually temporary fixes.

The closing aid system, as with most systems fitted to the W140 are just overly designed and overly complex, which is what makes this car so beautiful.

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A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]

There are tons of posts on fixing that system. Like this one:

http://v12uberalles.com/Closing_Assist_Pump.htm

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Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

Almost the victim of a 3rd pump, I followed the instructions, and it has been over three years without a hitch. The guys at MB confirmed that the pressure switch is the culprit sometimes, but overadjusting it could cause havok with the other elements. They also confided that NB wont let them open the pump or tweek it for liability issues.
If you look at it it has safeties, purges the lines of moisture, resets the elements.

I know it sounds hard to beleive.. But.. Really..This is an easy fix.. This is a circuit that simply resets closing aid system a pre determined time every time after the car is started. Simple.. And it works beautifully.. No need to replace anything for any reason..

I have had mine working for almost 2 months now. It works flawlessly. Perfect!! Enjoy the ride....

The old trick was to pull the fuse to reset the system.
This works up until the pump gives out all together. The system will fail between resets and at a shorter and shorter interval.
Ultimately you need to replace the pump.

Actually.. There are several reasons for the system to quit working. Pump failure or eventual failure of the pump is the least likely and for sure the most expensive and not needed. The pump will age and so does the grease, lines, and fittings. Here are the reasons for most of the closing aid failures. Cold Temps, Barometric changes, and fitting / connection mirco leak, and aging pump. The problems also occur with new S class but not as frequent. The system I am using takes care of all these problems and works beautifully with out any pump replacement. As for pulling the fuse and replacing it when the problem does occur. Well. Yes. You can do that. But I do not have to do that.. Not ever... But if you want to pop the trunk, open the fuse panel, search for the fuse, pull the fuse, replace the fuse every time you have a problem.. Then.. go for it !! I chose to have my system fixed so I never have to do that and my doors work perfectly. In the new S class, if you pull the fuse to reset the motor, you will reset a lot of other things as well. Keep that in mind...And.. Enjoy the ride !!!

lemme guess... the plug and play thingy simple resets everything every time the circuit is triggered.

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85 190E 2.3(SOLD)
86 230E (-->300D) sold
87 300D (-->300TD) sold
68 250S w/ a 615 and manual tranny (RIP)
87 300TD (SOLD)
95 S280 "The KRAKEN" (Turbo 2.9 602 transplant) traded
86 190E 2.3... current project

locry, spot on! And that approach will still let the pump run for 10s until it times out.
And it is the prolonged running thats killing the pump. So, I for one, would not
recommend this solution at all.

br,
syljua, with a properly adjusted pump...

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1998 CL500 W140
1984 230E W123

...and looks like you DO have an interest in this economically;
http://www.peachparts.com/shopforum/showthread.php?t=8442
Yeah, right, Mercedes would buy this...

not so best regards,
syljua

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1998 CL500 W140
1984 230E W123

Yes. I am the engineer that designed the circuit. It is a timing circuit that manipulates voltages to certain components at specified times during steady state conditions. Timing, voltage apertures, and steady state values I will not discuss, also, I will not go into the RC time constants and Vcc values or Time allowed for Steady State . Those are all engineering parameters that mean nothing to those with door closing aid Issues or problems. This is not a fix for everyone with closing aid problem.. But it is for most. . Circuit design is copyrighted and there is Patent pending on the physical aspects. It works beautiful. I am excited that there is a fix for the closing aid. But.. You guys can do as you wish . I am trying to help and let those know with closing aid that there is a fix. This is exciting for those that have this closing aid problem. At any rate.. If there is anyone with a door closing aid issue and need help, you can IM me or contact Star Tech Mercedes in Denver. There.. Done.. I hope those that need help see this before the post is pulled. I am sure that is the objective is to pull the post. You guys or site owners should have a swap and shop section then for posting services and products for sale or trade.. That is.. If you really want to help those with mercedes.. Just a thought.. Thanks.. Enjoy the ride..

14 years ago i was going to install a push putton that would break the A+ line, it seemed a little dorky. After replacing pums tweeking the sensitivity works like a charm

Seems like all have forgotten that it doesn't have to be the pump!

It could be the CAA . . . and if it's bad . . . there's no TRICKS that will fix that problem.

Check MENU #28 to refresh your memory.

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Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

I beg to differ. My system has run for 5 years without a single failure to close a door since performing the shut-off pressure switch adjustment. I would place adjusting the switch in the "easy" category, especially with the detailed instructions available.

Brett

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1997 S600 sedan