Boot lock mechanism microswitch

[Zeek333]

Hi , last week i experienced a failure with my boot mechanism. The boot closed until the point that the soft close should take over .. it didn't. After dissasembly of whole lock mechanism, turns out that one microswitch is broken (photo).
Problem is, that is impossible to buy new one anywhere. In service told me, that only solution is replace whole lock mechanis for 700 euros. I can not believe that i will have to pay 700, because one microswitch for 2 euros failed.
Do you have any idea how to solve it, or where to find it?

[fmorelli]

Couple thoughts for you to possibly research:
1. Are there any markings whatsoever on the microswitch?
2. The Z4 uses other microswitches for the top; you might research those and see if there is another one like it. I'd start in realoem.

You might find an equivalent. For example, look at the second photo here:
https://www.ecstuning.com/b-genuine-...h/54348226659/

Filippo

[fmorelli]

If you are handy, and you know that switch is bad, I might suggest you diagnose the switch. If you are gunshy, find a friend that is electronics savvy to help - the tests are not complicated and you are not asking a huge favor.

Three wires are going to tell you if the trunk is open or closed. This will help: https://www.youtube.com/watch?v=YN_kV2h-a04

Using a multimeter you can check if the switch is functioning - that is, if it is telling you when it is open, and when it is closed. I would use the multimeter probes at the base of the switch. If the switch shows open and close, I would test continuity on each wire, or you could simply retest using the probe at the end of the wire.

I believe you have several possibilities:
- you have a broken wire
- you have a contact issue inside the switch
- you have something physically broken with the switch or mount
- you've misdiagnosed the issue

Note ... the problem could be downstream of the switch - so for example, the broken wire could be on the loom to which the switch loom connects.

Good luck and report back.

Filippo

[Zeek333]

I am not good in this "small" electronics. And it is difficult to find anyone who can do something like that. Even in classic car service, firstly they didn't want to disassemble it. Everything what I know is from them (broken microswitch).
Microswitch from realoem looks really very similar but I need to know dimensions and also if function is the same. In my switch circuit is disconnected when is in pressed state (opposite to normal switch).

[NoQuarter]

Originally Posted by Zeek333

In my switch circuit is disconnected when is in pressed state (opposite to normal switch).

Most switches are able to be connected either normally open or normally closed. You simply choose the appropriate wire to use.

[Alesk]

Hello Zeek333,

I have exactly the same probleme, the same micro switch is broken.

Have you found this component ?
If yes, can you give me the contact please?

Thanks a lot :-)

[jesper.g.larsen@me.com]

Hi

Sorry to reply to this old post, but it seems as many have the same error with the boot soft close mechanism.

I had the same error and found a solution - use a micro switch from an E36.

The part number is: 61-31-8-363-693

BMW uses the same size micro switch for the boot lid and the only difference form the e36 micro switch to the same micro switch in my e93 is the colors of the wires.

No need to buy an entire boot lid assemble for 700 euros.

[RobbiZ4]

Originally Posted by jesper.g.larsen@me.com

Hi
...use a micro switch from an E36.
The part number is: 61-31-8-363-693 / BMW 61318363693

Interesting.
There are only 2 wires visible on all pictures of this spare part. On the left side of the E89/E93/F33 locking systems a switch with 3 wires is required.
Could you please explain, how you solved this?


From my experience, only 1 to 3 wires of these switches will break, not the switches itself. What happended to your switches?

[john180565]

Originally Posted by RobbiZ4

Interesting.
There are only 2 wires visible on all pictures of this spare part. On the left side of the E89/E93/F33 locking systems a switch with 3 wires is required.
Could you please explain, how you solved this?


From my experience, only 1 to 3 wires of these switches will break, not the switches itself. What happended to your switches?

Hi. I have the same problem. The switch only uses the two outer wires which are the normally open pair. The third wire would probably be for the normally closed contact but I didn’t test that. Looking at the rear of the boot, the right hand side has two wires and the left, three. Just connect the outer two on the RHS.

[RobbiZ4]

The 3rd wire on the left is for the trunc lights.

[TripleBlack]

Guys you're going to have to excuse me for reviving this old post but considering how prevalent this issue is across various models it could help a lot of people.

Thanks for discussing it so far. This and a few weeks of heavy google searching and video watching has helped me figure out that the above would be the area to target before i even took the boot lid apart.

My passenger side micro switch had worn and separated wiring inside the rubber boot.
I'm in two minds whether I should solder or crimp the wires but I definitely want to extend them a bit.

Can any of you identify what size / gauge or awg for the wiring I need to get? I must have missed this class in school and the wires dont have any writing on them.

[bigendbob]

Originally Posted by TripleBlack

Guys you're going to have to excuse me for reviving this old post but considering how prevalent this issue is across various models it could help a lot of people.

Thanks for discussing it so far. This and a few weeks of heavy google searching and video watching has helped me figure out that the above would be the area to target before i even took the boot lid apart.

My passenger side micro switch had worn and separated wiring inside the rubber boot.
I'm in two minds whether I should solder or crimp the wires but I definitely want to extend them a bit.

Can any of you identify what size / gauge or awg for the wiring I need to get? I must have missed this class in school and the wires dont have any writing on them.

Which switch, the one connect behind the boot badge rondel, or one of the two on the retraction motors. Just extend with any old wire and reconnect.
Best to solder.
https://z4-forum.com/forum/viewtopic.php?t=91766

[RobbiZ4]

Wires for replacement:
0.25mm² (~23AWG) LIFY wire quality is the better choice, not silicone. LIFY is high flexible, where as silicone is more temerature resistant.
https://www.litze24.de/produktinfos/kab ... n/awg.html

Be cautious!
There is no known replacement for the two microswitches on the left and on the right! Crimping is not an option at all, as there is no place in the bended area.

The white housings pushed over the two microswitches can only be removed after driving the two motors into a center position, not at their end position.

Use a 9V battery on pins 1&2 of each 5-pole motor plug to drive it.

[TripleBlack]

Hi both, thanks for replying. I missed it whilst researching my options vs costs.

In the end I purchased soldering heat shrinks that do both things all in one go and a heat gun.
After tearing through various types of spare cables, I found a slightly thicker equivalent wiring in a power cable for e-bike battery chargers and connected it all up.

The mechanism worked immediately with minimal movement or flexing required by the wiring. I just need to figure out the best option for protecting the exposed wires now. Avoiding electrical tape is the aim at the moment but I may just have to settle for that.

[RobbiZ4]

Originally Posted by TripleBlack

Hi both, thanks for replying. I missed it whilst researching my options vs costs.

In the end I purchased soldering heat shrinks that do both things all in one go and a heat gun.
After tearing through various types of spare cables, I found a slightly thicker equivalent wiring in a power cable for e-bike battery chargers and connected it all up.

The mechanism worked immediately with minimal movement or flexing required by the wiring. I just need to figure out the best option for protecting the exposed wires now. Avoiding electrical tape is the aim at the moment but I may just have to settle for that.

Well, congratulation for your succes.

BUT:
This is a perfect example how it should NOT be repaired!

• More flexible wires are recommended, not thicker ones.
• Don't use these monster shrink parts, as there is no room for it in this moved area.
• Use the white clips (strain relief) to save the 3 wires against tractive forces.

There is no known replacement available for these 2 microswitches! If your construction will break for the 2nd time, the shrinked connectors may destroy the remaining rest of the 3 wires next to the switch's housing.

That's my solution:

[TripleBlack]

Originally Posted by RobbiZ4

Well, congratulation for your succes.

BUT:
This is a perfect example how it should NOT be repaired!

• More flexible wires are recommended, not thicker ones.
• Don't use these monster shrink parts, as there is no room for it in this moved area.
• Use the white clips (strain relief) to save the 3 wires against tractive forces.

Originally Posted by RobbiZ4

There is no known replacement available for these 2 microswitches! If your construction will break for the 2nd time, the shrinked connectors may destroy the remaining rest of the 3 wires next to the switch's housing.

Hi, I appreciate everything you've stated.

-The wire is just one size up and I checked with my companies e-bike mechanics and they said that for this particular application there would be next to no affect on the current resistance. However, you are right, the thicker wire won't flex the same but I would argue that the flexing is the reason we are all in a similar boat.

-Regarding the image that you uploaded, the movement path drawn is exaggerated. ( I'll upload a video for anyone else doing research. ) You may be right about the soldering heat shrinks but right now they look as though they will last. I'll know better once I wrap them up in the next 48 hours.

-Because the tear in the wires occurred very close to the microswitch, using the white clips as normal is not possible. I do however plan to add zip ties in to the mix like you did.

-Lastly, I can get my hands on a few of these parts for far less than the BMW fee. So the plan is to get my hands on a few to last me however long I intend to keep this car.

Edit: So I couldn’t upload a video or .gif without jumping through hoops so here are two images of position 1 and 2 showing how little the wires moved.

[KennyP]

i just soldered those wires together manually and used the thinnest heatshrink as minimally as i could to insulate each wire...

i did have those sleeves with a solder ring in them (i dont really know how they are called in english, so this ruff translation from my native language), that "Tripleblack" used aswell but they were too big, cumbersome and not flexible.
Also i did not have to extend any wires...

One thing i have to say.. If those wires broke on one side already.. they will break on the other side soon too. For me it took like 3-4months from initial fix to have trunk issues again and on the second time those wires were broken on the other side. After fixing both sides i havent had any issues and its been over a year now since the last fix.