roof end-switches

[paul_frings]

Hi,
I have a problem with the electrical roof that turns out to be (too?) hard to solve. At some moment I got error 1101, 1111, 1110 and 1100. Reset works only on 1100 and 1100.
I Removed the inner protection of the roof, have access to pump, camper control unit and hydraulic control unit. I checked the fuses, and tried to check the end-switches. My problem is that the end-switches have nearly infinite resistance ~10MΩ and no short to ground. In theory this could be a broken cable, but I doubt this would occur in all 4 at the same time. The other option is that I'm missing something, are these end-switches normal reed-contacts or some more complicated electronic circuit inside? Could anybody me tell how to test them electrically since none of them seems to be a closed dry-contact.
Regards,
Paul

 

[Loz]

If it's all four, have you checked the earth connection on the hydraulic control unit?

 

[paul_frings]

Thank you for your quick reaction, but the only grounding I see on the hydraulics unit is the thick black cable (on the black connector) and that seems OK. Any idea how the sensors work? Cabling from the hydraulics control unit is 2×3 conductors to left and right side of the roof and they seem OK. It might be that the control unit itself is not functioning correctly, but would like to check the sensors before.
Regards, Paul

 

[paul_frings]

Hi,
I found the error in the end, the electronic unit is OK, the end-switches are OK(they are not simple open/close switches but GMR devices, you need to apply 12V to them, with magnetic field from the cylinder the current is 3mA, when no magnetic field the current mounts to 13mA). I checked the 30A fuse and measured the voltage on the control unit, everything seemed OK. HOWEVER when you draw current, i.e. want to open or close the roof, the voltage drops to nearly zero → bad contact somewhere! Finally I found the bad contact: a solder joint (made by VW!) in the cable below the driver seat (left seat in France). Pictures enclosed. Once the right diagnose the repair was simple: a new cable.

 

[capt kirk]

Good find, well done