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Roof Shell 2 stops closing, throw fault code A68B - my way to upgrade wiring harness

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cra3y
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Roof Shell 2 stops closing, throw fault code A68B - my way to upgrade wiring harness

Post by cra3y » Mon Aug 27, 2018 6:37 pm

Disclaimer: I'm not native English speaker, please forgive me my lingual mistakes :) Thanks!

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: "Microswitch, roof shell 2 closed, left"

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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):
Image


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.

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

Image

Image
Last edited by cra3y on Tue Aug 28, 2018 6:06 am, edited 1 time in total.
Best Regards
Chris

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cra3y
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Roof Shell 2 stops closing, throw fault code A68B - my way to upgrade wiring harness

Post by cra3y » Mon Aug 27, 2018 6:37 pm

I bought complete roof arms with hydraulic and electric harness (with sensors and microswitches too) to scavenge connectors, sensors (hall sensors - yes! the expensive ones), 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 shell, that dock into front, Dach2 is the secondary roof shell, with heated window in the back:
Image

Below is my short 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
Image

b) Dach2 is in on transition to closed position (on the back lid)
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c) The transition of Dach2 is completed and Dach2 is stowed on back lid.
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2) movement of the whole pack (Dach2 and Dach1) into the boot section.

The following photos are from this section:
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a) Dach2 is stowed on Dach1 - both in upper position - view from inner side of hinge
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b) Dach2 is stowed on Dach1 - both in lower position (stowed in the boot) - view from inner side of hinge
Image


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):
Image

- second cable section (2 wires)
Image

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".

Image

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

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

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

Image

Image

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 :-)
Last edited by cra3y on Tue Aug 28, 2018 6:08 am, edited 3 times in total.
Best Regards
Chris

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Smartbear
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Roof Shell 2 stops closing, throw fault code A68B - my way to upgrade wiring harness

Post by Smartbear » Mon Aug 27, 2018 6:47 pm

Hi, good fault finding Chris-are you sure your larger radius bends won’t cause the loom to snag anything when it’s all in situ? :?
Rob
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cra3y
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Roof Shell 2 stops closing, throw fault code A68B - my way to upgrade wiring harness

Post by cra3y » Mon Aug 27, 2018 7:30 pm

I'm quite sure that it should have some clear space to extend a bit - I will check this soon as I will find some time to do this mod in my car (in 99% in this week).
I will post more details later.
Best Regards
Chris

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Roof Shell 2 stops closing, throw fault code A68B - my way to upgrade wiring harness

Post by markplant » Mon Aug 27, 2018 7:44 pm

Good write up
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Roof Shell 2 stops closing, throw fault code A68B - my way to upgrade wiring harness

Post by cra3y » Fri Aug 31, 2018 10:11 pm

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.
Image

Image

Left side:
Image

Image

Right side:
Image

Image
Best Regards
Chris

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Roof Shell 2 stops closing, throw fault code A68B - my way to upgrade wiring harness

Post by carjerr » Sat Sep 29, 2018 6:13 pm

Very good job. Congrats!!!
Regards.

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