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2003 sl55amg
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88 Posts
Discussion Starter #1
The fuse for the trunk soft close function is in a tight spot behind the passenger seat below the storage bin. Seems like I usually end up bleeding when pulling it out to reset my system. I can't seem to locate the air leak that makes this a weekly ritual. This is a real pain when I can't raise or lower the top because it thinks the trunk is not closed. So I made a switched fuse assembly I can reach by simply opening the storage bin lid (from the drivers seat no less) and flipping the switch off and on. This makes the soft close function for the trunk work again for a while so I can easily raise the top like if it starts raining. Obviously this is just a bandaid approach, but it is cheap and totally reversible if I change my mind and want to spend a bunch of money to get it fixed right, which I don't at present.
So all you need is a fuse tap, some wire, an inline fuse holder, a 20 amp rated switch, some blade connectors (male and female) and a crimper tool. I made it about a foot long, and fed it up through the bin cover at a conveniently broken off plastic keeper thingy at the rear. I just taped it in place rather than drill a hole for the switch. The blade connectors are a bit too wide to fit in the fuse tap where the fuse should go, so I just ground off a bit to narrow them. The red wire at the fuse tap is just cut off since it is not used.
Now this may not be rocket science, but it took me a while to figure this out. There are no "make a fuse a fused switch" videos on youtube.
Not your cup of tea? Just look away.
 

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Current: 2003 SL55 Obsidian Black, 2007 ML500 Silver. Former: SL500, 560SEL, 450SEL, 300SEL 6.3
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135 Posts
Hi CBR,

It's much easier to disconnect the consumers battery in the boot/ trunk.

Lift the floor of the boot/ trunk and secure it with the hook provided then use a 10mm open ended spanner to disconnect the negative terminal.

Replace it after 30 seconds

No cut hands!

... Until you get around to repairing/ replacing the lock

I tried the repair but it didn't last long... just bite the bullet and buy a new one

Good Luck

Peter
 

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Registered
2003 sl55amg
Joined
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88 Posts
Discussion Starter #3
Hi CBR,

It's much easier to disconnect the consumers battery in the boot/ trunk.

Lift the floor of the boot/ trunk and secure it with the hook provided then use a 10mm open ended spanner to disconnect the negative terminal.

Replace it after 30 seconds

No cut hands!

... Until you get around to repairing/ replacing the lock

I tried the repair but it didn't last long... just bite the bullet and buy a new one

Good Luck

Peter
Somewhere I read that you should first disconnect the starter battery before the consumer battery, not sure why.
I suppose you are right about getting a new lock mechanism, I'll wait until it's not raining.
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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19,168 Posts
No - other way around - disconnect the consumer (trunk battery) first, before disconnecting the starter (front) battery.

Have you worked on the trunk latch?

 

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Registered
2003 sl55amg
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88 Posts
Discussion Starter #5
Oh, I guess I had it backwards, thanks.
Yes, I have sealed up the trunk latch everywhere. The PO had sealed it but missed a few spots. I don't hear any hissing. I thought it was fixed but then I installed a battery tender recently which keeps it charged up fine, but I have to open the trunk to disconnect it, then the soft close function ceases every time, I don't see how it should be related, but it seems it is. Once reset, I can trip the first lock position by hand when its open, over and over, and the second pull down part closes like it should until I hook up and remove the battery tender. Then the release won't open the trunk at all unless I use the key. This was driving me nuts, ergo the fused switch idea. I just hate to throw away more money and potentially not solve the problem.
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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19,168 Posts
I will bet you still have a leak. You should also check the diaphragm housing on the latch, It can crack and leak. Some people will use epoxy to seal and close it, but I used zip ties:

 

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Registered
2003 sl55amg
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88 Posts
Discussion Starter #7
I'm sure there is a vacuum leak somewhere, I'm just not convinced it's at the latch. The diaphragm unit was epoxied in place by the po, so I added a bunch more all around it since I couldn't remove it to get at the 6th port under it. I'm using a two part plastic specific expoy. I'm sure you know, intermittent problems like this are best DIY unless you like burning up hundred dollar bills only to have it turn out not fixed later. My switch solution is keeping my blood pressure from peaking.
You know that "Unforgiven" line, dyin ain't much of a livin boy.
 

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R230 SL350 Presnt, Past - W208 CLK230K 2000, W203 C Class, W202 C Class, W210 E Class, W201 190E
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1,459 Posts
I have replaced three trunk units, and must have taken them out to glue up more than 200 times..
I found one of the air lines for PSE pump was kinked and caused the time out E fuse fault. IF you do not have leaks, you possibly have a broken impeller on the PSE pump which is common. If you check Youtube it will become clear.
 

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Registered
2003 sl55amg
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88 Posts
Discussion Starter #9
You have my deepest sympathies! I can only imagine your level of frustration with this problem. I have reached my own personal level of frustration, and my switched fuse solution is some sort of victory for me. Perhaps as time passes I will be able to calmly replace some parts, but not yet.
 

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Registered
2003 SL500 silver
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91 Posts
I think your solution to this problem is a great idea. I just removed my trunk latch yesterday and glued up all the suspect areas (nothing really looked bad, but I went thru the motions). Now the pull down is working; it would last about three days after a reset. I'll check it every day to see if the glue fix works. If not, I will be installing a switch on the 20 amp fuse.
I plan to purposely blow a 20 amp fuse and solder wires to each side of the exposed fuse legs, then re-insert in the fuse slot. From those wires I will install an inline fuse holder for the new 20 amp fuse, the a switch for the disconnect. I haven't decided where to run the switch yet, but I'll find a convenient spot.
Thanks for sharing your ingenuity with the class.
 

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Registered
2003 sl55amg
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88 Posts
Discussion Starter #12
I think your solution to this problem is a great idea. I just removed my trunk latch yesterday and glued up all the suspect areas (nothing really looked bad, but I went thru the motions). Now the pull down is working; it would last about three days after a reset. I'll check it every day to see if the glue fix works. If not, I will be installing a switch on the 20 amp fuse.
I plan to purposely blow a 20 amp fuse and solder wires to each side of the exposed fuse legs, then re-insert in the fuse slot. From those wires I will install an inline fuse holder for the new 20 amp fuse, the a switch for the disconnect. I haven't decided where to run the switch yet, but I'll find a convenient spot.
Thanks for sharing your ingenuity with the class.
Thanks.
BTW, I tried working with a fuse at first. Soldering metal encased in plastic didn't work very well. A fuse tap is like $3.49 and works much better. Blade connectors are a bit too wide so I ground off about 1/4 of one and it makes a solid connection into the fuse tap where a fuse would go. Just need 2 of those. Good rainy day project.
 
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