2002 mercedes cl500 PSE (Central Locking/Vaccum pump
So I know these cars fairly well. When I bought this car I got it for a very good deal. Upon inspection of the car I knew there was already a leak in the PSE Central Locking System vacuum pump when buying the car one of the cables that opens up the trunk was cut so when you would open the trunk you would hear the vacuum hissing, it's invisible cut that you can see. Whoever had the car before me knew there was a problem with that so they converted the trunk to Springs versus having the actual pump and lock mechanism open the trunk. Also when I first got the car all of the central Locking System worked perfectly fine on the key fob and inside the car, the headrest would fold down perfectly fine and go back up perfectly fine, the rear sunshade work perfectly fine, the passenger door suction door works fine however like I said the trunk did not work because of the line being cut and converted to Springs and the driver side door did not suction so there must be something wrong or another line to cut to that door as well I'm not sure.
Now that all that is out of the way here is what's going on this morning when I went to go unlock my doors they unlocke, but when I went to go lock them it would not lock to the key fob and I wasn't sure what was going on it wouldn't unlock or lock. So I sat inside the car trying to use the central Locking System button that wouldn't work my rear sunshade would not go up all this points to the PSE pump. I checked fuses in the rear Sam and all seem to be in working order. Also key fob works... It still sets alarm and all lights blink when setting or disarming alarm!
Now this is my solution and route that I was talking about that I may want to go with the car now I have found a used pump on eBay that I could easily replace myself and I have been advised since it's not a new pump I would not have to reprogram it, however if it was a new pump I would have to reprogram it to the car. I was wondering about deleting the whole PSE pump all together and just getting an aftermarket alarm so that I can unlock and lock my car, would that work? Because in all honesty I don't care to have the vacuum doors and the headrest being able to go up and down however I would like the rear sunshade to work and I didn't think that was connected to the PSE unit.
I know this is a very long post but I'm just trying to get some input before I put money into the car. Thank you very much hoping someone can help here.
maybe to make it simpler what I'm really asking is since my PSE vacuum pump Central Locking System is not working and the key fob will not unlock or lock my doors can I get an aftermarket alarm so that my locks will unlock and lock with a new key fob the top aftermarket?


My car - same model/year as yours - experienced some of the same issues. When I got the car everything worked except the soft-close on the driver’s side. Then, I couldn’t lock the car with the key fob. Followed by not being able to unlock the trunk. Then, I was blowing the fuse for the pump.
When I finally decided to replace the driver’s door locking mechanism - it was decidedly shot. Huge leak due to the cracked vacuum housing. Once it was replaced, all worked fine except the trunk. It was intermittent in deciding to work or not.
I removed the pump housing and tore down the pump. It actually didn’t look too bad. The motor and vane pump is a small part of what’s in the box. The rest is electrical solenoids for the individual vacuum lines. Seemed like lots of opportunity for an electrical issue somewhere. So... I bought and installed a new, complete vacuum pump box.
Everything worked perfectly.
Bottom line... my input would be the issue is probably an easier fix than you might think. The door mechanism will need to be addressed and the trunk has been molested enough to maybe not be able to be returned to normal. The trunk line will at least need to be capped.
Not what you ultimately asked, but I’m not sure you want to go down your path.


I doubt the door issue is a cracked line - but, a cracked vacuum chamber cap. Replacing the door mechanism is, indeed, a fairly big job. But, be patient and careful - hopefully with a helper - and it'll get done. There's a good thread on here somewhere (maybe a sticky) that I used to follow. There are kits on eBay for the just the vacuum cap. But, I found it difficult to remove/replace without breaking a tab. So, I just replaced the entire unit.
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if you have access to the Star mercedes diagnostic systems, you will copy the settings from your old pump in DAS, then you can "paste" these settings to the new pump once you plug it in. we call it a "teach-in" process. this process helps because if you do not address the missing systems from your car, the pump can run into overtime, overheat and subsequently fail
as far as the rear shade,this is not controlled by the vacuum system
Regarding the door locks, they are vacuum controlled so i assume an aftermarket lock set will be quite difficult to retrofit...i would expect it to cause unwanted issues with reliability and such
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