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details of PSE replacement process

NB. If dome light issues brought you here: (courtesy of @Christopher Goodwin )

On the connector to the dome light
Pin 1 is the cable to the boot light (goes to +12V when the doors or trunk are opened)
Pin 2 is the chassis (so should always be 0V)
Pin 3 is the control signal from the lighting controller (N10-3) This should go to +12V when the doors or trunk are opened.
Pin 4 is permanent +12V from the battery via fuse 9
Pins 5 & 6 are not connected

Pin 3 supplies power from the lighting controller N10-3 when the doors or trunk are open, and I have +12v there all the time until time out, then it could be the N10-3 that is bad, not the PSE?

[EDIT to add vac codes:-
Thanks to @Dave2302

A lot of the list below isn't fitted to R170 but this might be good to put somewhere for reference as it will apply to all PSE's on all MB's .............

MB abbreviations for PSE Functions:-

FKS = Head Restraints
KAF = Head Restraints
HECK = Boot (Trunk) Lock
TD = Fuel Flap
MKL = Left and Right Front Seats
FT = Right Front Door
BFT = Left Front Door
FOL = Left Rear Door
FOR = Right Rear Door
SK = Optional Security Boot (Trunk) Locks

Now in the R170 case it really won't matter if you get 'em wrong, as their are only 3 so some functions must be interconnected, ............

If weird things happen swap a couple until it works right ;)

If you choose to learn a tad, get a small Vac Pump like "Mity Vac" and apply a Vacuum to each pipe in turn, see which of the Door Buttons moves and when, label that pipe, go to next pipe ....................

etc etc so now you know which pipe does what you can look at the above listings on your PSE Pump and plug 'em in :)

HTH :)_



* Administrator (Premium Member)
37,884 Posts
Cheers for your efforts, Decca.

Edit by Myk for an alternative but possibly related issue & fix:

Original post by @Tesla

Tesla, post: 4693958,
I followed all the links I could find regarding this topic and none of them answered my problem.
Battery flat, recharged and then central locking would not work.Well I can tell you now that it had nothing to do with the flat battery ( red herring). I checked all the fuse and all were ok, However I was unable to find the fusebox listed in the boot (trunk). I disconnected the PSE unit 4 plugs and 3 hoses. took off the bottom plate and no water damage to the PCB.
small amount of verdigree on the power connector but nothing cleaned and put back. still no joy. So being an engineer I decided to strip the PSE down 3 small torx screw hold the cover on. the motor felt warm so using a Sealey PP1 tester applied voltage to the motor and low and behold it was stuck. I removed the 3 brass phillips screws from the pump front cover. revealing the 4 small carbon blades used for the compressor. these i removed and kept safe. I then removed the pump outer ring (pump body) this allowed me to spray WD40 on the top of the motor allowing the liquid to penetrate along the shaft, I also sprayed some behind the pump backplate (front of motor). then i started to rotate the motor by hand . after 5 minutes I applied voltage to the motor and it rotated slowly and kept tripping. the tester. Do not worry it seems that this unit uses quite a bit of current, more than the tester allows for and rotates slowly. I replaced the PSE in position connected all the hoses and connects and low and behold the central locking now works.
the moral of this story is start with the PSE and work backwards it will save you hours. Please note that by applying the voltage directly to the motor terminals the PCB does not need any input and therefore is fairly safe proceedure.
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