SL R230 PSE/Central Locking Problem'ish.

[Nile Griffith]

Hi Kids!!

"An SL R230 with a PSE problem? Surely not" I hear you cry in unison. Well here goes, a call out to the hive mind so to speak.

Problem/Symptom.

On opening car from outside with remote key fob, drivers door (RHD) does not unlock, plunger does not raise. Closing the car from outside with key fob, all doors lock (well there's something).

Inside the car WITHOUT ENGINE RUNNING. Using central locking button on dashboard, as above. Passenger door unlocks but not drivers door. All doors lock.

Inside the car WITH ENGINE Running. Again using dash mounted central locking button, all doors lock and unlock without problem.

Initial diagnostics.

No audible signs of air leaking.
Battery in boot shows 12V when measured. Engine running 14v at battery terminals.

Observations.

The working sound/tone of the PSE pump is noticeably different when the engine is running as opposed to when working from battery power, assumption is that the extra 2v is turning the electric motor just that bit faster.

So brotherhood of the Teutonic'ally frustrated. Any thoughts? I'm against lifting off the door panel (cos' they never go back the way they came for starters) as if it was a lock issue the the problem would be consistent whether engine was running or not and I can't hear any air leak when listening to the door.

If it was impeller issues with the PSE pump, would the extra spin that 14v provides the Pump's motor with, be enough to overcome any issues, but all the other locks seem to operate fine (although the boot has always been a bit slow to activate/release).

I'm inclined to err towards an issue with the solenoid inside the PSE pump that opens/closes air flow to the drivers door lock, but..........

What I am trying to avoid is just blindly wading in pulling stuff apart, stuff that on twelve year old vehicles that doesn't always want to stay together as originally intended. So if anyone out there has had a similar issue I'd love to hear of it and what your fix was. Or maybe I just bite the bullet and sell a kidney to fund a new PSE pump.

Thanks in advance to all.

 

[LostKiwi]

It does sound as though the pump is perhaps a bit marginal.
It would be useful to get pressure readings with and without pump running.

 

[peterws1957]

^ This exactly. I doubt you would be able to hear a small leak in the pse pump, so you are working a bit blind with these things. Worthwhile having a look at the connections to the pump I found one on ours had become dislodged. If you are going to dismantle the pump it would be wise to get a pressure gauge, since even very slight adjustment of the assembly screws has a marked effect on the efficiency of the pump. Search YouTube there is a very detailed video on this subject.

 

[Nile Griffith]

It does sound as though the pump is perhaps a bit marginal.
It would be useful to get pressure readings with and without pump running.

Hi Lost Kiwi.

Might well be worth a punt. The thing that keeps poking at my sense of logic with this is that it's consistently the drivers door lock that generally fails to operate unless the engine is running. One would assume that German engineering would have ensured that air pressure delivery was uniform across all of the pneumatic circuits. For instance there does not appear to be any issues with the seat bolsters (and with my weight on them too) so adequate pressure is obviously there.

Maybe it's the lock mechanism in the drivers door itself, just being a bit sticky and that extra oomph that the running engine gives is enough to overcome the added friction. Anyone played around with the mechanism? is some form of grease/lubrication needed? Is there an easy way to do this without taking all of the door card off?

Mentally I keep coming back to the idea of some sort of fault in the solenoid that governs the valve for the air circuit to the door lock within the PSE pump body. Does anyone know if that despite each lock having it's own (yellow) airline, if the two door locks are effectively fed from the same valve/solenoid supply. If that's the case the fact that the passenger door operates correctly rules out the "sticky solenoid" hypothesis.

 

[LostKiwi]

Not sure on the 230 but the 129 is definitely the same supply to both doors.
I can't see why they would split it in the 130 either.

 

[SL63 Mark]

My money's on the PSE pump. They have a limited life span. Mine went at about 12 years old, the same age as yours. It's a 12V electric pump. Likely it is not putting out sufficient pressure for whatever reason. Logic/guesswork will not predict symptoms of failure. You need some diagnosis from a STAR equipped Mercedes independent.

 

[Nile Griffith]

Not sure on the 230 but the 129 is definitely the same supply to both doors.
I can't see why they would split it in the 130 either.

Hi Lost Kiwi!

That follows my train of thought, why would you have two separate valves/supply? which sort of leans the emphasis towards a "sticky" door lock mechanism, as the passenger side operates without any issues off the same level of air pressure/vacuum release.

I feel the dreaded door card removal is getting closer.