My trunk will not open. I can`t open it with the key or the trunk button. The light on the button will not come either. Which fuse controls the trunk switch. My fuse chart is in my trunk. DOH!!

 

If you can't use the key then its not a fuse right???

On My car only the Master FOB valet key works on the trunk. you have to push up and turn. It feels kinda hard but it will open.

Does your soft close work on your doors? if not The fuse for your PSE is what you should be looking for. it controls the trunk also.

 

where is this fuse for the PSE

 

According to the guy who did mine, its buried somewhere UNDER or BEHIND the Accessible fuses on the back footwell.

I had my PSE pump replaced under warranty last year in December. I recently had the same issue as this guy with my trunk but my doors stopped working also so I took it back and that's how I found out about the key in the trunk thing.. BUt I had a blown fuse replaced, and they did a check to see why it blew and came up with nothing so who knows what happened there.

 

I too had to open the trunk with the manual key because the battery drained out. The key worked but it is akward to operate. Your problem is not a fuse problem if the key does not manually work. My key worked with all the power drained. Once I opened the trunk, I was able to access the battery and properly jumpstart the vehicle. Good luck.

 

I agree .. the key should open it regardless (it's mechanical not electrical or pump driven). That said, the fuse is under the rear passenger seat, behind the light (just pull the panel out). It's the 20amp fuse (yellow one) .. easy to replace.

FYI .. if it's the fuse your door locks, auto door close, rear seat head rest release and gas tank lock won't operate either .. so if these work and you can't open the trunk with the key .. it's something else.

Best of luck!

 

Well I tried the key again & the trunk still won`t open. Does anyone know which fuse or relay controls this area?

 

Its not a fuse causing the problem. I have had this exact problem on two cars in the past week. One of them I got today. Last week a guy shut the trunk on his luggage strap, so after about an hour of trying every possible thing to get the trunk open manually, we ended up sending it to the body shop to get it cut open and a new decklid put on. Fortunately today, I managed to get it open with the blade key. Usually it is the trunk latch that fails, and wont release. I could attempt to tell you a way to get to the cable manually, but its quite long to explain and a bit mechaniclly inclined. Try the dealer. I know they have ways of getting it open.

 

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.

 

Hey I got the trunk open. I was turning the key to the right. Thanks!
When I open the trunk,I hear air coming from inside the trunk. Could it be an actuator?

 

I had same problem and just fixed it myself. Take the liner off of the lid. you will find a latch assembly that has a black plastic air cylinder attached to the side of it. The crappy plastic let loose that keeps the 2 halves of the piston together. I tryed epoxy.. didnt stick.. finally I took a piece of heat shrink tubing and that fixed it.. works good now..

 

That was it. I put some aircraft epoxy on that cylinder & for now it`s holding.

 

Good grief! I had the same problem after letting the battery die this winter. I tried to open the trunk manually but no luck. I then read forum after forum that basically said the trunk is not affected by electronics if you try and open the trunk manually with the key.

I tried rotating the key clockwise and counterclockwise but the button would not depress. I finally figured out the answer today.

The button/lockset was already in the depressed position. I didn't know that because I never open the trunk except electronically. I was in the process of trying the key in the reverse position when the button popped out to the normal "start" position. I turned the key counterclockwise to the 10:00 o'clock position, pushed the button and the trunk opened.

I wonder how many other people have been confused by this? Anyway, thanks all for chipping in. Now I have to wait and see what resetting I have to do to the electrical systems after it charges up.

If anyone has any tips please pass them on.

 

What follows is courtesy of Skylaw -

This info is so handy, although I have posted it before, I'm doing it again.

First, the ECU reset procedure that Johnny7623 recommended is included in my owner's manual in the battery change instructions - along with some additional info on things that may need to be reset (it helps to read those manuals!!) However, not everything is addressed there, so here goes.

Windows, seats, mirrors, steering wheel position (easy entry/exit) and the like can be reset by running them fully in one direction, holding the switch at full travel for approximately 2 seconds (or longer), then running to the opposite limit, holding for about 2 seconds (or longer). It is not unusual to have to do this after the battery is disconnected. The positioning of many of these features is controlled by a Hall's Effect generator, a simple device that counts revolutions of a motor shaft, and it must be set to register the proper number of turns to reach both limits of travel.

Synchronizing Head Restraints:

If the power supply was interrupted (battery disconnected or empty), the head restraints are no longer adjusted automatically. To resynchronize the adjustment feature, turn electronic key in steering lock to position 2, move the seat completely forward and the head restraint fully down, and hold respective buttons for approximately two seconds.

Synchronizing power windows:

If the power supply was interrupted (battery disconnected or low), the windows cannot be opened or closed by the Express feature. To resynchronize the express feature, press side of power window switch to resistance point until the window is completely closed and hold for additional 2 seconds. Repeat procedure for each window. The automatic full opening and closing procedure of the windows should now be restored. (Note: This sometimes works as well for problems with manual operation of the windows, but not always).

Synchronizing sliding/pop-up roof:

If the power supply was interrupted (battery disconnected or low), or if the sliding/pop-up roof is blocked during closing/opening procedure, the system has to be synchronized. To do so, turn electronic key in steering lock to position 2, move and hold switch in direction (3), until the sliding/pop-up roof is completely raised at rear, and hold for additional 1 second.

Synchronizing ESP (ECU):

If the power supply was interrupted (battery disconnected or empty), the BAS/ESP malfunction indicator lamp may be illuminated with the engine running. Turn steering wheel completely to the left and then to the right. The BAS/ESP malfunction indicator lamp should go out. For more on resetting the entire ECU, see Found it! ECU Reset Procedure.

Synchronizing remote control:

The remote control may have to be resynchronized, if the vehicle cannot be locked or unlocked. To synchronize insert electronic key in steering lock. The remote control should once again be operational."

Synchronizing Steering Column Height/Easy Exit:

Steering wheel height - basically the same procedure, but with a caution. Move your steering column down SLIGHTLY, and if you can then bring it back up to where it started (but not higher), then you need to reset the column with the simple procedure below. HOWEVER, if it goes down slightly, but will not go back up at all, do not try the reset - it probably will go fully down and not come back up! You may not be able to get into the car to drive, if that happens. Get it serviced.

Run the steering column full down, and holding the switch down for about 10 seconds after it reaches the lowest position; then run it back up fully and hold the switch up for about 10 seconds after the column reaches its upper limit of travel. You may need to do this several times. That should reset the limits in the Halls' Effect generator, and your column should function normally.

Seats (easy exit) - try running them to the limits also; however, the seats slide back in the easy exit mode only if they are pretty far forward in the first place. if they are back beyond certain limits (set by Mercedes), not sliding further back is normal operation.

Not all cars have easy exit, and for those that do it must be selected in the MFD (instrument cluster) menu.

 

bumping this up from the dead, as i just encountered this issue.

i can only open the trunk manually via blade key in the tumbler. all 4 doors and trunk soft close work, 20A fuse reset didn't help, motor can be heard at trunk when remote, door & trunk buttons are pressed. from what i've read, this likely narrows my issue down to mechanical failure of the trunk latch.

has anyone had any experience in fixing or replacing the latch? any help would be appreciated.

TIA

 

If you take the cover off the trunk lid you may be able to see what the problem is. The latch assembly is pretty simple and you can access it fairly easily.

 

One more related question. After replacing the battery on w220 s55 the automatic trunk closer will only open the trunk half way up. Is there a reset to get the trunk to raise fully? I have searched without any luck yet.

 

Theboogers have you checked the trunk limiter in the little window below the odometer. There is an option that will allow you to set the height of the trunk from the steering wheel controls. Make sure the limiter is turned off.

 

Wasnt in the menu thanks
Found you have to hold the remote trunk button extra five seconds with key in ign to reset trunk to regular height open.

 

Here is an interesting scenario that just happened to me. Can't figure this one out.

My trunk was completely opening with the key fob and the release button on the trunk itself. It will also close with those two buttons.

Now here comes the fun part. I opened the trunk with the release button on the driver's side door and it will only open halfway. Also, after using the key fob button and the button on the trunk itself they will now only open the trunk halfway.

I have tried the reset by having the key in the ignition and holding the door release button for about 10 seconds but that doesn't help. I even disconnected the battery for about 1/2 hour and went through the synchronization process but that didn't help.

Is it possible that the release button in the door is defective? This is where the problem started.

 

i just let the trunk open with the door button and then i closed it and held it a extra 5-10 seconds when it closed and it went to open all the way. it is discussed in the manual and the trunk partially opens incase you have a canoe on top of the car.

 

I checked the fuse and it looked fine once i put it back all i hear is a noise in the back of the car

 

Thanks a lot, this solve my issue with trunk!

 

I'm bringing this post back from the dead. I have a 2003 S600 and the trunk will not open without the mechanical key.

My opening/closing pump works well, but the latch will not unlock. The PSE pump works for everything else in the car. All massage, locks, soft-close, lumbar, and headrests operate. The latch does not.

I replaced the latch with a brand new part from the dealer ($304 wholesale cost) and it's still not functioning. I hear no air hissing anywhere in the trunk when I hit the button to open the trunk.

Where to look next?

 

Clogged filter perhaps? Is it possible to have a kink in that one line controlling the trunk? When I disconnect the air line from the wiring loom on the right side of the trunk and blow or suck (coming from the PSE pump, not the line going to the latch) it seems impossible. Should I be able to breathe freely through it?