[LukeHill]

Hi everyone,

I have a 1999 c280. Out of the blue, all of my door locks and my trunk release have stopped working. I'm assuming this is the vacuum pump?

If so, can anyone tell me where it's located so I can replace it? I haven't been able to find the information online.

I have seen a few posts that suggested it might be in the trunk. If so, how would I access it, as without vacuum, I can't get the trunk to open (even with the key).

Thanks in advance.

 

[georgebuhr]

Vacuum pump is located in the trunk, on the right side, to the outside of the battery. If memory serves, it is behind the fabric trim, and encased in a block of foam.


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[LukeHill]

Vacuum pump is located in the trunk, on the right side, to the outside of the battery. If memory serves, it is behind the fabric trim, and encased in a block of foam.

Thanks. So, since the trunk release is vacuum operated, how do I get into the trunk in order to replace it?

 

[Patman1]

Just push the trunk lock, it doubles as a manual way to open the trunk! If the trunk isn't unlocked, you will have to unlock it with the key.

 

[LukeHill]

Just push the trunk lock, it doubles as a manual way to open the trunk! If the trunk isn't unlocked, you will have to unlock it with the key.

Uh oh... I've tried that, but it doesn't work. I can turn the key in the trunk and even make all the windows open, but I can't actually get the trunk to open.

Any other ideas or am in a really bad spot now?

 

[Patman1]

Does the vacuum pump run when the central locking is activated? I believe the fuse for the vacuum pump is actually in the engine compartment fuse box (which would make way more sense than having it in the trunk, like for example when your situation happens!). Check the fuse, it's possible it blew for some reason, there might still be something wrong, but maybe with a new fuse it would at least allow you to open the trunk and continue diagnosing further.

 

[c180w20294]

View below picture in full screen.

Dec

 

[LukeHill]

Thank you so much!! That did the trick! I was turning the key all the way to the left, but instead just turning it a 1/4 of the way to the left opened it no problem. Very much appreciated! Now, I can start trying to diagnose this vacuum problem.

 

[c180w20294]

Your key should not turn past the position in the 3rd picture above, which is about 10:30 on a clock face, unless it was forced with a tool like pliers.
Check the fuses in the fuse box close to car battery and try unplugging ALL the electrical connections, for 20 minutes, that might reset the pump electrics. Check the electrical connections for corrosion and clean up if needed.

Keep your keys in your pocket so you don’t accidentally shut the boot lid with the keys are inside.

Dec

Above, a pump from a 1994 W202

Below, a pump from a 1998 W202

 

[LukeHill]

Well, it's fixed! Being able to get into the trunk changed everything... it was a single burnt out fuse in the trunk.

Thanks again for taking the time to help me!

 

[Patman1]

And keep that lock lubricated! Mine is already seized, tried to spary in some oil but it didn't help. I'm in for a surprise if my vacuum system fails. I was thinking of going to the dealership soon to get a new lock put in the trunk specifically before something like this happens Glad to hear it worked out, I also had no idea you could stop the trunk from opening like that, it's pretty cool!

 

[c180w20294]

If you don’t already do so, spray into the lock keyhole slot with the boot lid in the fully open position, that way gravity helps to deliver oil into parts of the lock you can’t get to while the lid is in the closed position.
Give it a squirt every day and leave the boot lid open for 5 minutes to allow the oil to spread fully into the lock mechanism. If the key blade fully enters the lock barrel then you are ½ way there.

If your car is 1996 then your lock is a little different from the one illustrated in post #7, as far as I can remember you can’t:
-Lock the boot with the keyhole slot in the horizontal position.
-Slamming the boot shut doesn’t automatically lock the boot, the car has to be locked centrally in order to lock the boot or the key has to be turned to the right.

There is a guide here… W202 Boot Lock Fix. | Mercedes-Benz Owners' Forums
Don’t take the lock apart if you can avoid it; free It up with oil if you can.

Dec

 

[LukeHill]

Much appreciated. Thank you!