I have to use the key to open the trunk.
 

With the key out, even in the unlocked position, I can't open the trunk. I hear a click and it seems to go back to the locked position.

I can only open it with the key in and pressing the button.

Is there any way to set the lock to just open without ever using the key?

edit--this is for the w123

open the trunk, and push the locking system into the unlocked position should work. you may have to disconnect the vacuum actuator.

I have a 240 sitting on blocks that's like this, I'll look at what it takes before I cut it up...

Ok well that's a relief. I thought it was just me... I have had this issue with every MBz I've owned after my w116.

thanks! you rock!

Me too. One of the few aggravations of owning these cars. Sometimes it's mind boggling. One day it works without the key and then not. I cannot figure out the logic.

These cars have a mind of their own. Just get on their wavelength and be happy. :rolleyes:

On mine One of the Door Actuators has a leak and also the Main Lock Vacuum Switch on the Drivers Door. That was enough to keep the Trunk from opening reliably and I have no Trunk Key at all.

Replace the bad Vacuum Parts parts and everthing functions as it is supposed to.

The Vacuum Lines that go to the Trunk and Fuel Door Actuator are on the Right side of the Car on the front Floor under a removabel Plastic Channel. If you dicsconnect the Lines there you can reconnect them later without haveing to open the Trunk; like in case you loose your Trunk Key.

Pic borrowed from another Member.
Were it said got lost is the lines for the Fuel Fill Door and the Trunk.

I suppose there's a chance that someone got the vacuum lines reversed so the trunk lock has vacuum pulling it into the locked position at all or most times.

I would like to just disable it completely. I would like to be able to open the trunk without using the key.

You can always disassemble the lock, remove the pins, and reassemble. This should allow you to open the truck simply by pushing in on the button without using a key.

what pins? will the pins be pretty obvious when i take out the lock assembly?

have you ever removed the lock/button mechanism? Easy for the leaver that connects that to the vacuum element to be come detached.

same thing happened to me.. caused symptoms similar to what you're describing.

FYI, an '85 w123 with the factory alarm system may have a different actuator/configuration due to the emergency release cable under the rear seat.

You should be able to disconnect the vacuum lines going to it and be able to open the trunk without the key in the unlocked position. However, this also means you have to lock it manually.

If I can recall it well enough to describe, it seems like when you turn the key to the 'unlock' position it doesn't change the mechanism setting inside... until it does, one time in 20.

Maybe it is the vacuum actuation holding it locked, but I would have to wonder at how as I thought the trunk got its vacuum from the door circuits and mine are inop, plugged with golf tees at the moment (shame, shame, I know).

Brainfart: Or have I got this turned around, the vacuum unlocks not vice versa... ahhhh....