W140 Locking

First thing to do is to 'reset' your door lock... by simply removing the fuse for the door lock and reinsert.

Thanks Tiger, but i can,t find a fuse for the locks, I have checked the fuse panel under the bonnet and can,t see any relating to the locks. I hope it isn,t in the boot because it will not open with the key. Where might I find it ? Thanks Chu

The fuse is in the boot. Have you tried using the switch to open the boot? Besides removing the fuse, you could disconnect the battery, but it is in the boot, also.

There is a button on the central console. It has a glyph of an opening boot on it. If that doesn't work, I would try to fiddle with the key to get the boot open, otherwise you're pretty much screwed. Does the key turn when you put it in the lock?

Sorry to sound boring but I suggest contacting a Merc garage/workshop if nothing offered in the forum works.

DAS

To send an e-mail directly replace "spam" with "schmetterling"

Thank you all for your advice. I think I may have been supplied with the Valet key when I bought the car and that is why I cannot open the boot manually. The previous owner thinks he may have the Master key, so I am waiting to see if he can find it before I try anything else. Again thanks for your help. Chu

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Central locks are operated by a vacuum pump located under the rear seat passenger side. The power is coming from fuse 11 in the trunk passenger side. The pump is used for a number of other things than central locking (backup assist, retractable trunk handle etc.).

If you cannot open the trunk, because the lock operates only with central locking, you need to access the vacuum pump.

Get hold of a hold of a manual vacuum/pressure pump and connect it to the yellow vacuum line leading to the trunk lock. Apply pressure/ vacuum to lock/unlock respectively (I don't remember which pressure or vacuum causes lock or unlock).

In this way you can at least get the trunk openen.

By removing and reinserting the fuse (of course a good one), you will reset the computer in the vacuum pump assembly, and it should start operating again, if it works at all.

The rear seat is removed by sliding the small red handles under the front of the seat to the sides and then lifting the front of the seat. Take care when you remove the seat. Wires for heating may be connected to it. Just disconnect the plugs then.

Central locks are operated by a vacuum pump located under the rear seat passenger side. The power is coming from fuse 11 in the trunk passenger side. The pump is used for a number of other things than central locking (backup assist, retractable trunk handle etc.).

If you cannot open the trunk, because the lock operates only with central locking, you need to access the vacuum pump.

Get hold of a hold of a manual vacuum/pressure pump and connect it to the yellow vacuum line leading to the trunk lock. Apply pressure/ vacuum to lock/unlock respectively (I don't remember which pressure or vacuum causes lock or unlock).

In this way you can at least get the trunk openen.

By removing and reinserting the fuse (of course a good one), you will reset the computer in the vacuum pump assembly, and it should start operating again, if it works at all.

The rear seat is removed by sliding the small red handles under the front of the seat to the sides and then lifting the front of the seat. Take care when you remove the seat. Wires for heating may be connected to it. Just disconnect the plugs then.

(1) Vacuum to lock and pressure to unlock. (2) Master key also works on glove box. That is an easy way to tell what kind of key you have. It used to be master/valet keys have different handle. Master has rectangle and valet has oval. I am not sure how the shape changes since remote came out. All our W202 keys (with remote) are master.

Jens wrote:

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Thank you Wan-ning Tan for the information. My key does work in the glove box and is rectangular so it seems i have the master key but for some reason wont open the boot, I have sprayed lots of lube into the lock and tried with a lot of force to get it to turn but with no luck. I will remove the rear seat at weekend and try to open the boot by putting pressure on the pipe as suggested. Many thanks for your help. Chu

Rear seat will not let you gain access to trunk. There is a gas tank between the trunk and back seat and a full sheet of metal wall between back seat and gas tank.

Does your key turn the trunk lock? If yes, Insert key, turn all the way and push in the button at the same time. If that doesn't work... try the other way.

No the key wont turn in either direction I was going to access the vaccum pump under the rear seat and pressurise the pipe going to the boot to try to unlock it as suggested previously Thanks for info Chu