W210 1997 Central Locking - Won't Unlock

[Nomar]

hi guys, I did try searching on the forum but couldn't find an answer to this so pls help!

I got this problem with my central locking, it locks fine with the key fob and the button on the dash, but it won't unlock. I can hear the PSE working when it is locking, but when i tried unlock, it seems the motor just "buzz" once then nothing.

Any ideas would be much appreciated! If i replace the PSE, does it need recoding?

 

[Nomar]

can anyone help pls?

 

[Dieselman]

More likely the pump motor is on the way out but will work one way.

 

[Dec]

Give the pump a whack with the head of a screwdriver at the moment it makes the “buzz” sound. This might give some clue to the fault.

Dec

 

[Nomar]

Dec, do you mean it may be that the motor is stuck one way? I took the motor out last night and spray WD40 in the brush area, then put everything back in and tried again in the car, it is still only unlocking the car but not unlocking.

I disconnect the yellow pipe that splits into 6 (i guess they are the pipes to the 4 doors, boot and petrol cap) and test the air pressure, when it locks it continue to suck air in until i put my finger over the nozzle, it then stop after a second or 2, when trying to unlock, it just blows a "puff" of air out of the nozzle then stop. It seems the motor is working but something is stopping it from continueing to blow?

Any ideas please?

 

[Dec]

It might be a good idea to dismantle and clean the pump “propeller” it could be stuck one way alright, when the pump motor runs it runs in one direction and “sucks the doors locked” with air through the yellow tubes.
When the pump is run again, it runs in the opposite direction and “blows the doors open” by blowing air through the yellow tubes.

The pump propeller… seen at start of video below… could be sticking in one direction, in your case, unlocking, put up a picture if you take it apart BE SURE to put it back together EXACTLY the way it came apart, you will see 6 or 8 “spikes” or “blades” on the propellor, its thease blades that do the sucking and blowing. See… YouTube - BENZ Vacuum pump inner motor assemble instructions

Also, some pictures of the “propeller”/ “blades” … http://www.bikersoracle.info/PSEPumpMotor.pdf ... yours is probably different, again, be sure you put the propeller blades back EXACTLT the way you found them, if any are broken then put up a picture.

Dec

 

[Nomar]

Thanks for the photos illustrations!

I have open up the PSE and did a few things, I removed 3 screws that build up the pump stack and checked the pump rotor and vanes, they look ok so i spray abit of WD40 to clean it up abit, put it all back together and cut power wires so i can test it with a 9V battery. It does blow and suck ok with the 9V battery test! so i reconnect the power wires and tested in the car, however, dissapointingly it is still not unlocking, just a puff of air as before.

I took the circuit board out and spray it with a little WD40 and give it a wipe down just in case it is condensation, still no joy, so I left it on a radiator over night to see if that helps...

I will upload some pictures i took while i take the thing apart later.

What is the common way to upload picture here?

 

[Dec]

Your vacuum motor would seem to be in working order, the fault must be elsewhere, perhaps at the unit’s connection plugs or damage on the PCB tracks or solder joints.

Pictures of both sides of PCB will be usefull.

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Dec