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1998 CLK320 Sport & 1997 CL500
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13 Posts
Discussion Starter #1
Since I purchased my 1998 CLK320 last year, I have not been able to open the boot using the switch in the centre console nor the button on the remote. When using either of these, a humming noise can be heard from the boot area, but the lid doesn't spring open as I would like. And ideas as to what may be wrong/what I can do to fix it, to avoid replacing an $800 lock? I thought it may have been separately locked, but I'm unsure.
 

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Premium Member
2004 CLK 240 Coupe
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11,367 Posts
Problems with your door & trunk lid locks can be either: a) mechanical, b) electrical, or c) pneumatic.

Operation of these locks is initiated electrically, but actuated pneumatically from your PSE unit (A37)in the trunk. The PSE produces a pressure/vacuum for the following systems:

Central locking (p for opening, v for closing)
Remote Trunk Release RTR (p)
Retractible rear head restraints (v)
Multicontour seats (p)

First, can you lock/unlock your trunk easily with the mechanical key stored in the remote? Next:

a) mechanical. Is the lock latch lubricated, and also mating perfectly with the striker eye? This can be adjusted sideways.

b) electrical. As you can hear sounds of operation, this might be OK.

c) pneumatic. Does your switched rear head restraints work (fold) OK. They use the same pneumatic output line from the PSE as the RTR.

It could be a faulty pneumatic element on the trunk release switch (s15/1) which might be obtainable separately.
It is not difficult to remove the trunk lid lock (2 screws) to inspect the operation of the trunk lock housing. Maybe the pneumatic line has fractured or fallen off.
 

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92 190e 2.6 Sportline, 2005 clk55
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1,197 Posts
First, can you lock/unlock your trunk easily with the mechanical key stored in the remote?
I read in the owners book that this is a a valet feature. if you lock the trunk with the key then it can not be openend with the fob or the inside button.
 

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Premium Member
2004 CLK 240 Coupe
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11,367 Posts
I read in the owners book that this is a a valet feature. if you lock the trunk with the key then it can not be openend with the fob or the inside button.
I think that you have misunderstood the book.

The mechanical key in the remote key is the emergency key. It will open a locked driver's door, or a locked trunk (when turned counter-clockwise). It does not reset the ATA (anti-theft alarm), nor does it have anything to do with valets. There is (or used to be) another key that was described as a valet key. That would not open the trunk or a locked glove box.
 

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1998 CLK320 Sport & 1997 CL500
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13 Posts
Discussion Starter #5
I can easily open the boot lid with the mechanical key. However, the rear head-restraints dont fold when I press the switch. Thank you very much for your advice. I will inspect the boot lock shortly.
 

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1998 CLK320 Sport & 1997 CL500
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13 Posts
Discussion Starter #6
Everything seemed to be in order, or nothing seemed to be out of the ordinary. What exactly should I be looking for? Thanks again.
 

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Premium Member
2004 CLK 240 Coupe
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11,367 Posts
Matt - where are you located? Please add this to your profile. :)

OK. With the trunk lid lock unbolted, but still connected to its electrics & pneumatics, what happens if someone operates the internal switch for trunk lid release? Does it try to operate?

If nothing, if you pull off the pneumatic line and repeat the test, do you feel a pressure at the end of the line?

If nothing, you may have to look into the pneumatic line from the PSE control module (A37). The unit is located in the trunk (RH side) behind the lining. It is wrapped in a white foam rubber cube. You know that the unit works, because the doors lock/unlock. So the problem might be just the pneumatic line that feeds the trunk lid lock (with pressure) and the rear head restraints (with vacuum)

Try first to examine the condition of the pneumatic lines without removing them. Does the PSE sound as if it is working when you operate your remote, and the internal trunk lid release? If you eliminate a leaking pneumatic line, you might have to look for an electrical problem.
 

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'00 w163 55 amg (sold) '02 w208 55 amg '03 w163 350 inspiration
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711 Posts
...the rear head-restraints dont fold when I press the switch...
not to beat this off-topic but this sounds separate and electrical re: center console malfunction. just .02 cents before taxes.
 

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1998 CLK320 Sport & 1997 CL500
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13 Posts
Discussion Starter #9
I'm from Australia, land of the worlds crappiest cars, I know.

With the boot lid open and lock unbolted, nothing happens at all. The humming noise can no longer be heard either. And no, there is no pressure when the line is disconnected.

I tried to access the unit behind the trim but I wasnt able to. It definitely sounds as if it is working both when I press the remote button and internal switch but only when the lid is closed.

I may have to take this one to the local dealer, unfortunately. But thank you very much for your assistance.
 

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Premium Member
2004 CLK 240 Coupe
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11,367 Posts
Matt.

The fasteners holding the trunk side liner come off very easily. Use a screwdriver to lever the head upwards. Then the body can be pulled out.

Ref the pnuematic line at the lock. No pressure = no operation. Chances are that something is adrift/fractured between the PSE and the lock. :thumbsup:
 

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Registered
1998 CLK320 Sport & 1997 CL500
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13 Posts
Discussion Starter #11
Hmm... seems as though I overlooked one of the fasteners, no wonder it seemed stubborn.

You are correct, a small white cable has disconnected, right up near the rear seats.
 

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1998 CLK320 Sport & 1997 CL500
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13 Posts
Discussion Starter #12
A little bit of electrical tape and its working perfectly.

Thank you so much for your guidance!
 

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Premium Member
2004 CLK 240 Coupe
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11,367 Posts
I'm pleased that you managed to fix it. :)

Too bad for us Brits about the cricket at Brisbane & the Open in Melbourne today though.... :(
 

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1998 CLK320 Sport & 1997 CL500
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13 Posts
Discussion Starter #14
The tennis was very frustrating... Can't say I have any idea about the cricket though.
 

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clk 320 2000 model
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85 Posts
i have clk320 2000 model i am having trouble with central locking i have checked all fuses front and boot all ok the boot lock wont work had the pump out and cant tell if there is problem seats dont inflate head rest are they suppose to move??? also read that the siren can cause problems ??? have been told to get it a scan but not sure this will tell the problem
also read that if u get updated pse it has to be updated in computer??
 
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