Folding mirror repair (switch pin)
 

My driver side mirror doesn't stay folded so while I was trying to see what's causing it, I broke off the wire in the tiny pin switch (attached photo). I'm going to try soldering it back but looks too difficult.
Would it be possible to purchase this part without having to buy the entire mirror unit?

I hate to say but you have to source a used one... BMW does not sell just that part, they sell the entire power mirror harness.

PS: keep that metal tang. you neve rknow when you may loose one. Always good to haev a spare

I've seen them on eBay UK. Give it a try...

An example. No endorsement...

BMW X5 E53 Folding Electric Side Mirror Sensor Microswitch New Fix And Repair | eBay

I have the same problem with my mirrors. My driver's mirror will fold and immediately go back to its normal position. I was unsure if you determined that the micro switch was the problem or simply a causality of your troubleshooting. Did you fix the problem?

The problem is just ficsator

For some time u can resolve ptoblem by your hand...just oush mirror forward and back in normal position and then press button shoukd work! If not...just replace ficsator... but u already broke something there :D

Is there another word for "fiscator"? I don't know what that is. Thanks for your response.

The thing or switch who fixes the mirror.. do not know in english... one of the rrason is that thing! U can listen when u fold the mirror by the hands! My was gone some where in wrong position!

Thanks. That's quite expensive.

BTW, what exactly does this switch do? Mine is completely disconnected but the mirror still folds, just doesn't stay folded. I'm thinking this switch wasn't the problem from the beginning and I I should not have even touched it.

that e-bay switch is NOT the proper one for the e53. the e53 switch only has 2 wires. I have played with it many times and I just tried a repair to one last week. the wire broke at the entrance into the black plastic. Not fixable at that point.
So I'm not sure why this e-bay version of the switch has 3 wires, but something seems to be not so plug and play.

That microswitch is necessary. It is what "tells" the mirror when it has reached the stop in the folded position and so the mirror will stop at that position.

Without the microswitch the mirrors will just continually fold in and then back out because the mirror motors (and whatever other electronics control the folding function) aren't getting their stop travel signal from the microswitch. I had to repair my metal tab or tang on mine to get the mirrors working properly again. Fortunately the wires did not break on mine. Hope you are able to find a replacement.