MB Medic Mercedes-Benz Repair Guides, Service, How To DIY
Have you locked the keys inside the trunk of your Mercedes-Benz? Maybe your key fob isn’t working, or your car battery is dead, and you are trying to unlock the trunk of your Mercedes-Benz. If your car battery is dead or the key fob remote has stopped working, you won’t be able to unlock your Mercedes-Benz or open the trunk.
In this article:
- How to open the Mercedes-Benz trunk when the battery is dead
- How to unlock the trunk when the key is not working
- Keys locked in the trunk How to open Mercedes trunk.
How to manually unlock the trunk of a Mercedes-Benz
If your Mercedes battery has died, the trunk switch or the key fob remote isn’t working; you can use this method to unlock the trunk.
Step 1Â
Remove the metal key from the key fob. You must slide the locking tab with your thumb and pull out the metal key.
Step 2
Insert the key into the trunk lock cylinder.
Step 3
Turn the key until you hear the trunk pop open.
Note: Avoid jump-starting your Mercedes-Benz by connecting the jumper cables directly to the battery. Instead, use the positive jumper starter terminal located in the jumper cable.
How to open the trunk if the key isn’t working or keys are locked.
What if you started replacing the battery in the trunk and accidentally locked the keys inside? Now you are wondering how I can open the trunk. Here are a few similar scenarios.
- The car battery has died, and the battery is in the trunk.
- You lock the keys in the trunk, and the battery is dead.
- Or you tried to unlock the trunk but can’t turn the key manually.
So what do you do? Luckily, there is another way to power up your Mercedes-Benz.
Get a locksmith to open one of the doors, then follow these steps.
Step 1
Release the hood by pulling on the hood release lever on the side of the dashboard.
Next, open the hood. 
Step 2
All Mercedes-Benz model years 2000 and newer have a jump start terminal inside the engine bay. Locate the positive jump-starting terminal if the battery is in the trunk or under the rear seat. This is how the positive jump start terminal looks on an E-Class W210.
Here is another example. 
Step 3
Connect a jump box positive terminal to the positive terminal and the negative jumper cable to a ground point or frame. Alternatively, instead of a jumper cable 
Now you can press the Lock/Unlock buttons on your Mercedes-Benz key fob remote to unlock the car or the trunk. You can even start the car this way.
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I own a 2000 C-280 with a w-202 chassis. I have no access to the trunk, the fob key won’t move on the ignition switch to any position, when I hook a donor battery to the positive terminal in engine compartment and ground.( I hope that is the correct connection).I don’t get the EIS to work, the steering wheel is unlocked but all I get on the dashboard is the bottom row miles and other lights to come on, no sound or zipping from the locking of the wheel. The heavy gauge black wire under a plastic cover on the shock tower or near it is the one am using to hook up power, interior lights come on radio works after I reset the code but nothing else, central locking would work when pressing the button . The mechanical key won’t open it either, I need to check the fuses and install the correct battery, how can I access or open the trunk, let me know please, thank you. Reinaldo.
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Hello my name is frank I have a 2007 E 350 and cannot open my trunk manually with key because tumbler is going around what can I do I am desperate and do not have money can I do it from the rear seat?
Oh and my battery is dead oh my god do not know what to do? Help plz.
my 1994 e340 trunk will not open with the key battery is good also speedometer quit oddamater works thanks
Hi,
Have a problem with my car 1999 S class model, the problem is the battery is not charging even when the alternator is working normally. what can I do
How was the alternator tested? You may have a bad voltage regulator.
Yes more simple than I thought..
On a 03 c230
Remove drivers rear speakers grill cover
Underneath is the subwoofer, unclip the 2 audio connections..
Ps Remember wich is wich if you reverse when connecting you will have no bass
There are push clips to remove subwoofer carefully manipulate it out
Now get a long stick and push the EMERGENCY green trunk release button behind license plate on the inside
I am a AAA service tec and I recently had a call where a member had locked thier keys in the trunk of thier E350. I was able to succeed in opening the door, however they did not have the pass into the trunk through the back seat. I was unable to get the trunk open for them and they ended up paying an expensive tow bill to have the vehicle taken to a dealer to get the trunk unlocked. Is the any way that I can open the trunk after the security system is activated to avoid this situation in the future?
Good question. You will have to get through the back seat which would be a lot of work and you can’t really do on the side of the road. If your battery is dead or the car hasn’t locked, I would recommend connecting a 12-volt source under the hood at the post/neg terminal and that will power up your Mercedes.
If it is valet locked
Yes more simple than I thought..
On a 03 c230
Remove drivers rear speakers grill cover
Underneath is the subwoofer, unclip the 2 audio connections..
Ps Remember wich is wich if you reverse when connecting you will have no bass
There are push clips to remove subwoofer carefully manipulate it out
Now get a long stick and push the EMERGENCY green trunk release button behind license plate on the inside