Hello everyone, I have a 2004 S500 and the central locking vacuum pump went out couple months ago...So, I bought a used one on eBay for $290 and it worked great. Now, it got fried again! the motor inside is literally fried...not sure what is causing the motor to get so hot. I'm suspecting the trunk lock as it's the only one that was not working properly...the soft close does not work and the chrome handle does not retract right away. I'm thinking of replacing the trunk lock as it may be the culprit! I need some help with the part number for these pumps...The original one that was in the car is 220 800 11 48 and I see many that look identical with other part numbers that end with 02 48, 05 48, 07 48, 12 48...Are they interchangeable? most websites list 220 800 12 48 as the part number for my 2004 S500...Not sure if this is an upgrade to the 11 48 that I originally had?? There are so many on eBay with 05 48 part number but not sure if it would work. Any help would be appreciated.

 

Just a quick thought. Blow some smoke into the vacuum lines to determine if they are leaking anywhere along the path from the vacuum pump to the various locks. If you find a leak it is likely that the vacuum pump recycled often to try to maintain the necessary vacuum and in doing so fried just as the first one did. You are likely to see smoke where the stress points are in the vacuum lines (often where they pass from frame to door or trunk) and it should be pretty obvious. If no leaks are detected I would check the voltage to the pump to make sure it is not too high.

Paul Curtis

 

I have a similar problem with my 2005 S430. I replaced one pump which started to blow the 20 amp fuse. Replaced again with exact same part number which seems to work. It locks the doors but will not unlock them. The soft close feature also does not function. Nothing happens to the trunk lock. The lid has to opened with metal key. After resetting a few times, the pump started to run continuously. Checked for hissing noises around the door locks and elsewhere. Found hissing noise coming from the front behind the command/control system, around the buttons (lock, unlock, etc.). I am going to remove the command system and check for leaks. Can anybody help me on this issue? Does anybody have a schematic of the whole vacuum/pressure/electrical system?