Centexrider

Hello everyone! In case you're wondering, I'm using the same username here as on a few motorcycle forums I participate in. Anyway, I recently purchased a 2004 S430 with 149,000 miles on it. It's obviously been well cared for and runs very well, as an S-Class Mercedes should. I'm aware of significant risks which can get expensive real fast, but I do significant DIY work, so am hoping to keep costs under control. The only significant problem with the car right now is the remote door locks. Not only do none of the doors (or trunk) do the "suck in" thing, but when locking the car with the remote, none of the door locks go down, making it a PIA to lock the car via the passenger door. When unlocking with the remote, three doors (slowly) unlock, and one rear door does not unlock. Also, to open the trunk, one has to use the small key. I'm presuming this indicates a faulty central door lock vacuum pump, but I'd like to see if there's any sort of troubleshooting guides out there for this problem, so any links or suggestions would be appreciated. Many thanks in advance!

MJ50

moved to W220 forum...

wallyp

Yes, there are many threads on this forum and the Benzworld forum on this problem. Both have "SEARCH" buttons at the top, and both have "sticky" threads telling owners to "START HERE".

pierrejoliat

There are many troubleshooting guides in the sticky posts including the W220 encyclopedia.sounds to me like your door and trunk actuators are leaking, try pulling the PSE pump fuse under rear seat, this will reset the PSE pump and reactivate the actuators in the trunk and four doors. You can then half close the doors one at a time to see which actuators are leaking air by listening at the respective door you close partially. Likely the rear door you mentioned does not lock is leaking so you will need a new soft close/door lock actuator there. Also listen when you partially close the trunk for an air leak, if you hear one that actuator is leaking as well.do you hear the PSE pump in the left front of the trunk running? Either way do not throw parts at it until you do the diagnosis, more could be working than you think. The pump will automatically turn off the leaking component for soft close.

Hope other more educated people chime in!

Centexrider

Great advice. Thanks!