Mercedes-Benz Forum banner

Door/Trunk locks just stopped working - Vacuum?

6134 Views 12 Replies 4 Participants Last post by  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.
1 - 3 of 13 Posts
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.


Above, a pump from a 1994 W202

Below, a pump from a 1998 W202

See less See more
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.

1 - 3 of 13 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.