To replace the old one you need to.
Vw t5 door microswitch.
The drivers door wasn t too difficult for me to dismantle and reassemble.
Ps i honesty think that vw engineers sit around on fridays with a round of beers and laugh at how many ways they can design insane obstacles for you and i to scream profanities while being locked out or window stuck open in a rain storm.
No external testing certification.
In my limited experience with these door modules i have not yet come across a micro switch that is actually broken they appear to be pretty tough.
When i unlock the van with the central locking button from the outside when i pull the handle to open the door it never works first time always have to operate it again to open it.
Open the tap fully remove the plastic lever pull towards the side with using a screwdriver or something similar pull the micro switch out you need a screw driver disconnect the cableunderneath.
Just to say that i managed to install this microswitch and it works perfectly in the original vw california tap.
Give it a try and good luck.
Ce for vehicle brands model.