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Discussion Starter #1
but could not figure out where to locate the pump for the central lock.
Please where is it located and what do I have to remove to get to it.

Also I understand that the close assist pump is located somewhere underneath the rear seat bench.
I can not clearly understand what has to be removed to gain access to the pump. I read about removing carpet from the trunk area??

So far I got the assist working for the doors but the trunk lid has no assist and all of the power locks are not working. I have to unlock by key.

Thanks for your advise.
Your text here
 

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94 s420 98 s420
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537 Posts
Thats great you got the close assist to work with the fuse trick. I believe the central lock pump is located under the rear seat not in the trunk. I hear my pump kick in when in total silence, after locking the car while inside using the consol switch.

you will have to remove the rear couch and its very simple, there are two red tabs that you pull out on each side and the couch becomes free. It would take less then a minute to remove. These would be located right behind your legs if you were sitting down on the couch, one to the left and one to the right. Good luck.
 

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SEC 600 V12 2dr COUPE (RHD) One of the chosen few.
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2,233 Posts
Goatman - 5/9/2005 9:53 PM

but could not figure out where to locate the pump for the central lock.
Please where is it located and what do I have to remove to get to it.

Also I understand that the close assist pump is located somewhere underneath the rear seat bench.
I can not clearly understand what has to be removed to gain access to the pump. I read about removing carpet from the trunk area??

So far I got the assist working for the doors but the trunk lid has no assist and all of the power locks are not working. I have to unlock by key.

Thanks for your advise.
Your text here
Brett San-Diego is the man to sort this for you try his gallery...or look at his pre posts..look in the knowlege base at the top of this forum...
 

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S600, ML55
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Discussion Starter #4
Yes the trick with the fuse got the pump in motion but the trunk does not work, so I have to trace the lines and see if there is a leak or if the pump module is the problem.

I found the fuse for the central lock but it is ok, so I assume a total failure of the lock pump.

I have the rear power seat hope that it will come out easy.

Thanks, I apreciate all input on this issue.
 

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Discussion Starter #5
Merc600sec - 5/9/2005 3:53 AM


Brett San-Diego is the man to sort this for you try his gallery...or look at his pre posts..look in the knowlege base at the top of this forum...
sorry I am new to this forum, I found the galley (its out at the moment), but where is the "knowlede base" located? I can not find the link to it
 

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Discussion Starter #6
OK, sorry I found Brett's write up about the close assist.
Thanks Brett
It helps...and yes the close assist pump is in the trunk not under the bench.

Question is there any article about how to troubleshoot the central lock system?

Many thanks[:)]
 

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1997 S600 (sold)
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4,660 Posts
No in depth detail on the central locking pump that I've seen since I've

been following this forum (a little over a year). You can try the search function some more. I believe comments have been made about motor brushes wearing out, and I think people have said you can replace the brushes (But, this is my poor memory working here). You'll just have to get to the pump under the rear seat and start to play around with it. I can't offer any advice on this pump. I've only had to work with my closing assist system.

For your trunk, you may find your trunk line disconnected and plugged by the previous owner like I did. But, again, you've just got to get in there and see what's up. It's easy to remove the trunk lid liner to follow the air line all the way to the latch. First, check the pump outlet for the trunk at the pump itself and see if that line gets any pressure when you simulate closing of the trunk. Then go from there.

good luck,
Brett
 

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Discussion Starter #8
Thanks Brett,
here is the update,
removed the close assist pump to adjust and test it. It works fine and I managed to adjust the pressure shut off. It was a little different with a very tiny screw that had a wire soldered to the top. the adjustment screw was glued and could not be adjusted without risking to break the plastic around it. So I adjusted the contact by bending it. I discovered that the trunk does not deliver a electrical signal to the pump. I will have to trace the micro switch. I connecte the trunk line to the left rear door port and operated the door to see if the trunk works. Yes it does work, so it must be a contact problem.

Next I removed the rear Bench to find the vacuum pum. I opened it to find it full of black residue from the motor brushes. The pump motor is worn out. I desoldered the pump wires from the circuit board and tested the motor with 12 volt Dc. It does not work. I could not open the motor to gain access to the brushes. The housing is crimped to the end plate with the brushes. Its a cheap little motor for such a expensive assembly. Next I visited the local dealer to find out that the central lock pump assembly would cost $1000 with discount applied!!!!!!!!! I told the parts man..no thanks.

German Star sells the pump for $ 475...
Anybody has a less expensive solution??

Thanks

[8)]
 

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1997 S600 (sold)
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4,660 Posts
You'll find the central locking pumps on ebay, too.

I don't know if the price is better than Germanstar.

Glad to hear you're making progress. I can't say much about the trunk sensor microswitch. I think you'll just have to remove the latch and have a look. One guy did say he found that a stereo installer had accidentally cut the wire to his trunk microswitch when he put things back together.

Brett
 

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Discussion Starter #10
RE: Getting closer to fix the central lock and close assist

Brett,
I will remove the cover from the trunk lid and measure with my trusted ohm-meter to see what the problem is. Will report next week what the problem was (hopefully).

I searched Ebay for the central lock pump assembly and found several for auction and buy now. I am comunicating now to find out if the pumps are new, used or rebuild.

Hope the central lock and all vacuum dependent circuits will work after replacing the pump. Anyway, I will update on progress to share my findings.

Werner
 

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1997 S600 (sold)
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4,660 Posts
You want to check the lower latch, not the latch in the trunk lid.

The switch that activates trunk closing is in the lower latch mechanism in the car body not in the trunk lid.

Brett
 

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Discussion Starter #12
RE: Oh..Ok, I did not know that the switch is at the lower latch...

that helps Brett,
It could be that, as you said, somebody cut the wires. When I removed all carpeting I discovered that a installer cut a bunch of wires from the old radio amp on the rear driver side in the trunk. He may have cut the signal wire running from the switch to the pump.

Thanks for the info![8)]

Werner
 
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