Dach 2 stop closing, throw fault code A68B - my way to upgrade wiring harness

[cra3y]

Hi
I had problem during closing roof process - the roof pack 2 (one with the glass, which open first/close last) stopped just before reach back lid and throw the fault code A68B, which means: "Mikroschalter Dachschale 2 geschlossen links"

I disconnected this switch and tested with multimeter:
- it has 0.05 Ohm when not pressed
- it has about 2.7 kOhm when pressed, so this switch is OK

This led my suspicious to cable and bingo ! The one was broken near upper hinge mechanism (image below):

This cable is very stiff and prone to crack, when You try to bend several times. I don't know, why BMW use this poor quality cables in such demanding places (when bending is very often). The red "oval" is the place, where cables is broken.

I cut the cable and replaced with new (temporailrly) in this section to check it will work or not.

And this fix works !! But ... My plan is to order good, industrial-grade 2 or 3 or more wires cable like chainflex® CF9 (https://www.igus.de/product/1013) which will able to withstand 5 000 000 bending cycles or more and replace existed ones (in both sides) in this area (images below) to prevent such problems in the future (because bending an tensions occurs in this area very often and existing wires will be broken sooner or later):

 

[cra3y]

I bought complete roof arms with hydraulic and electric harness (with sensors and microswitches too) to scavenge connectors, sensors (hall sensors), microswitches, hydraulic tubes and wiring harness for future usage and to learn, how to fix this damn thing .

Before I started, some info - Dach1 is the main roof, that dock into front, Dach2 is the secondary roof, with heated window in the back:

Below is my analysis of the weak points (where cable bends to much) in roof construction:

1) movement of Dach2 - the red "ovals" pinpoint the weak points. These bending points cause cable to bend over 160 degrees.

a) Dach2 is stowed on Dach1

b) Dach2 is in on transition to closed position (on the back lid)

c) The transition of Dach2 is completed and Dach2 is stowed on back lid.

2) movement of the whole pack (Dach2 and Dach1) into the boot section.

The following photos are from this section:

a) Dach2 is stowed on Dach1 - both in upper position - view from inner side of hinge

b) Dach2 is stowed on Dach1 - both in lower position (stowed in the boot) - view from inner side of hinge

3) My plan is to upgrade cable situation on these weak points to fix this for good:

a) I bought industrial-grade electrical cable: chainflex® control cable CF9 CF9.05.02 (2 wires 0.5mm2) and CF9.03.05.INI 52 wires 0.34mm2)

b) Prepare to replace the existing cables wires in this sections(cut existed one, solder in both side then wrap soldering sections using heat with shrinking tubes)

Left side of car:
- first cable section (2 wires):

- second cable section (2 wires)

On the right side of car - the same way, but there is another cable harness with 5 sensor/switches wires in small diameter and 2 with large diameter. The 2 large is for driving Dach1 motor-latch in the front, and these wires should withstand bending, but I'm thinking about replace the 5 wires in the same section as photo above.

4) My big concerns about the upper section of the Dach2 hinge

I have big concerns about the section marked in "A".

The hydraulic tube bend hard (over 160 degrees and stretched a bit) in this section, when Dach2 is stowed on the back boot lid:

I modified the harness situation by make more freedom in this section:

And how this look like, when Dach2 is on the way to Dach1 (to stow on the Dach1)

The bend is about 90-100 degree (before was about 160-170) and electrical harness + hydraulic tubes should withstand longer than before.

.

Time to apply modifications (mentioned above) in my car :-)

 

[RobbiZ4]

Great documentation, thank you very much! It will definitely improve my understanding of the roof details.
Did you buy those arms from eBay? I was watching a pair of it since months, but now it has disappeared.

 

[cra3y]

Polish olx.pl portal (a way smaller than ebay site, mainly for private trade). I boutgh the arms for about 170€.

PS: I took some pictures about roof locking system. If You want, I will share the details

 

[RobbiZ4]

Polish olx.pl portal (a way smaller than ebay site, mainly for private trade). I boutgh the arms for about 170€.

PS: I took some pictures about roof locking system. If You want, I will share the details

Wow, that was a deal!
Well, every additional background info shared to this forum is appreciated. Hopefully I will be able to give some infos back to you.

 

[cra3y]

Update: I replaced 3 pair of wires today: to microswitch left, right and to hall sensor (all in Dach2)

Wires were connected by using "Western Union" splice then clenched using small metal tube. Both wires were isolated by tape then isolated from environment using temp. shrinking tubes with glue.

Left side:

Right side:

 

[cra3y]

I also checked the hydraulic hose/line in bend sections and in one of them the outer shell (rubber) has some cracks but the inner core is ok. I secured this section using special rubber tape that vulcanize itself, so there will be less tension.

 

[RobbiZ4]

[...]using special rubber tape that vulcanize itself,[...]

Could you please specify the tape or post a link to it?

 

[MiSt]

I am not convinced that stiffening the areas of strong bending improves lifetime. Especially, I would never place a soldering point there, which gives 5-15mm of nonflexible length. Instead, I would replace the whole cable from the middle of one straight to the middle of the next straight, ensuring completely new and unworn material in the bend, where the predecessor gave in.

Just my 2 cents (or pennies, does not matter ...)

 

[cra3y]

The heat shrinking tubes (weatherproof) were like this
https://www.amazon.com/OTC-4814-106-Piece-Waterproof-Shrink/dp/B00BVL856I
I bought in polish "ebay" (Allegro) - It could be any weatherproof heat shrinking tubes.

The "special rubber tape that vulcanize itself":
SCAPA-2501 19X10M SCAPA - Band: selbstschweißend | TME Germany GmbH - Electronic components


PS: the stiffer areas (with connection to new wire + heat shrinking tubes) are located in places, where no bending occurs (not in hinge points/area), so it safe to use in this location (picture below - location marked with "S").