How do I get the trunk open when the release mechanism fails?

Tiny
DRIBAN
  • 2002 MERCEDES BENZ S430
  • 101,000 MILES

I have tried the button on the fob, the release switch inside car, and the metal key hidden inside fob. I have even tried to access trunk through back seat. I hear it is some strange pneumatic release mechanism. It used to work just fine. I can't get to a dealer, nearest is 4 hours away. A local mechanic wanted to cut through the metal behind the license plate. I only NEED to get in since my tail light bulbs are starting to burn out. Any suggestions?

Would there be a cable if it is pneumatic? I had the local mechanic try to get through the back seat. For some reason he gave up on that idea.

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Tuesday, November 15th, 2011 AT 12:17 AM

7 Replies

Tiny
PROAUTOTECH
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  • 295 POSTS

Try this, and make sure you're using the master key, not the valet key, it's the only one that will get you in. The trunk will open with the key if you operate it properly.

Insert the key and turn the blade slightly toward the left, approximately ten o'clock position and
then push upward. The trunk will be heavy to lift but it will come up. My Benz dealer had to educate me on this Friday. It may take a few tries to find the right spot with the key, but it works.

Yes, it's a pain. Sometimes you have to unbolt the latch completely from the inside. I don't blame him, he'll never be able to recoup the time lost playing with it. Do the rest of the door locks work? If not, you cold try to find the line that goes to the trunk, find a T or junction and try to put your own vacuum on it with a mighty vac. See if he's willing to give that a shot. The pump is probably under the hood Hopefully not in the trunk). Let me see if I can find some schematics.

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Tuesday, November 15th, 2011 AT 1:17 AM
Tiny
DRIBAN
  • MEMBER

Yes, the rest of the doors work just fine. Finding that air line would be a great start! It wouldn't surprise me if the pump was in the trunk area. The battery is there (.I'm praying it doesn't fail either!).

No dice on the key. Tried not just 10 o'clock, but all positions. I am wondering if it could be a bad relay, specifically #N on the fuse diagram. I found a fuse diagram for a 2000 model, which I hear is no different than the 2002. I am going to pull it and test it.

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Tuesday, November 15th, 2011 AT 1:22 AM
Tiny
PROAUTOTECH
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  • 295 POSTS

The key should work, so it has to be the latch itself if it doesn't. The key should override any pneumatic system. That's an educated guess by the way.

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Tuesday, November 15th, 2011 AT 2:29 AM
Tiny
DRIBAN
  • MEMBER

The mechanical lock definately has a problem. The owners manual says the key's range of motion should be from 10 o'clock (to open) to 3 o'clock (to lock). In my case, the key turns some what freely all the way around, and will keep going. Regardless, when the system failed, the trunk was not locked by the mechanical key. I just 'discovered' how to access the 3rd fuse panel under the rear seat. With better light tomorrow, I will investigate fuse #57. Which appears to be exclusive to the trunk mechanism.

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Tuesday, November 15th, 2011 AT 3:33 AM
Tiny
DRIBAN
  • MEMBER

I forgot to mention that although the relay tested fine, when I re-seated it, it didn't make a sound when trying to open the trunk with the fob. So with this, I will check the rear fuse box in the morning. I appreciate your help with all of this!

Relay N works just fine. I respect your guess, that it is the latch itself. But in theory, shouldn't I hear the electric/pneumatic system 'at least try' to pop it. Make a noise or something? (. It makes not a sound.)

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Tuesday, November 15th, 2011 AT 3:41 AM
Tiny
MHPAUTOS
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The pneumatic control is in the boot, so this is of no use, the electrics that operate the system use CAN technology so hot wiring the system is a no go as well, and the manual lock is faulty, wow where to go. I am wondering if the only option is to drill out the barrel and key and trip the lock, MB may have a better solution, ii would call them and explain the dilemma, there may be an over ride somewhere that we are not aware of, I would give them a call.

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Thursday, November 17th, 2011 AT 9:52 AM
Tiny
WILL ESTES
  • MEMBER

I would not admit this to just anybody but maybe it will help someone in the future. When you're changing your battery, DON'T close the trunk while you go to the store, even if it does look like rain. Wait for another day, because without power, the trunk will not open without help from your friends. The valet fob will not work, but the master key fob will. Thanks to the experts for the advice.

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Wednesday, April 4th, 2012 AT 7:29 PM

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