Roof closing problem - FIXED.

[Bill H]

Just had a problem on our 120i where the roof wont latch to the top of the windscreen when it closes.
The whole mechanism seems to work up until the final locking but then the hooks just dont move - so was then serenaded by the BMW bongs as you drive along.
AFter 3 days of intense problem determination have finally solved it - and I reckon it could be a common problem

The solution is one of the Hall Effect sensors on the mechanism had become displaced by a few millimeters, managed to push back in place and secured with a cable tie. The sensor that caused this is called "Tensioning bar extended" but what it really means is the hydraulic ram is extended that pushes the rear window up and down.
(Just tried uploading a picture of the location but not sure if it worked)
There are a total of 8 Hall sensors on the mechanism - these are on a RH drive car I presume they are the same for LH drive as well.
1 in the cowl panel above the windscreen
2 under the rear storage compartment on the LH side of the vehicle (looking forward)
5 behind the rear RH quarter panel (when looking forward).

These can be really difficult to find as some are only exposed at certain points as the roof goes up/down, there are 2 towards the back of the mechanism that are obvious when the storage compartment cover is up, a third can be seen from the same point but looking forward under the rams, a fourth is buried deep down near the seat belt , and the 5th was the devil - it was on the hydraulic strut itself and very well camoflaged, the cable to it was tied to the hydraulic lines and had pulled tight - it had pulled the sensor out by just a mm or two. I cut off the cable ties and tied the sensor to the strut itself.

[Bill H]

Originally Posted by Bill H

Just had a problem on our 120i where the roof wont latch to the top of the windscreen when it closes.
The whole mechanism seems to work up until the final locking but then the hooks just dont move - so was then serenaded by the BMW bongs as you drive along.
AFter 3 days of intense problem determination have finally solved it - and I reckon it could be a common problem

The solution is one of the Hall Effect sensors on the mechanism had become displaced by a few millimeters, managed to push back in place and secured with a cable tie. The sensor that caused this is called "Tensioning bar extended" but what it really means is the hydraulic ram is extended that pushes the rear window up and down.
(Just tried uploading a picture of the location but not sure if it worked)
There are a total of 8 Hall sensors on the mechanism - these are on a RH drive car I presume they are the same for LH drive as well.
1 in the cowl panel above the windscreen
2 under the rear storage compartment on the LH side of the vehicle (looking forward)
5 behind the rear RH quarter panel (when looking forward).

These can be really difficult to find as some are only exposed at certain points as the roof goes up/down, there are 2 towards the back of the mechanism that are obvious when the storage compartment cover is up, a third can be seen from the same point but looking forward under the rams, a fourth is buried deep down near the seat belt , and the 5th was the devil - it was on the hydraulic strut itself and very well camoflaged, the cable to it was tied to the hydraulic lines and had pulled tight - it had pulled the sensor out by just a mm or two. I cut off the cable ties and tied the sensor to the strut itself.

Further picture added

[lvfb]

would the location of those sensors be flipped for american cars? the one you said was on the left hand side for my american 128i is on the passenger side (right hand side)

[Bill H]

Originally Posted by lvfb

would the location of those sensors be flipped for american cars? the one you said was on the left hand side for my american 128i is on the passenger side (right hand side)

Sorry - i don't know, but I cant see a reason that BMW would flip sides.
It would be easy to see though, on the RHD UK car the roof pump is in the boot (Trunk) on the RH side of car looking forward, the wiring loom runs on the RH side of car as well - you can even see it where it runs under the edge of the roof fabric.
I've uploaded a couple of pictures of the location of my sensor and the wiring loom with the pinout on to the roof control unit.

Good luck -

[Josh-PA]

thanks for sharing this. I keep a bookmark folder of all the possible e88 roof issues. Knock on wood, so far I haven't needed any, but these posts will be valuable if/when I do.