Interesting Roof Issue (surprise, not working)

J

jdogg9981

Member
So I’ve been slowly getting the roof back to the point where it is operational. It previously had not one, but TWO hall sensors cracked and throwing faults. Replacement of these now has a CTM that is throwing no faults. However prior to replacing the sensors, the roof was in a “closed” but not locked position. Meaning that the top and shell (roof and windscreen units) where not locked in place and therefore able to be moved. Moving the rear shell on top of the roof in the “open” position allowed the rear module (deck lid) to open itself up when activating the roof open button. This however was where the operation stopped. While trying to diagnose, I moved the rear shell back into it’s “seated” position while the deck-lid was still open and pressed the top open button again. Strangely, this locked the shell into place.

I now have a roof that is closed and locked in place, but a read deck-lid that is open. The roof open button flashes red, but pressing it results in the hydraulic motor whining, but no actions taking place in the car. There are no codes in the CTM module, and reading the data-stream indicates that all sensors state the car is in the positions it is in:

Roof closed and locked
Shell closed and locked
Rear module (deck lid) open

Is there some “reset” procedure that I have to initiate to get the roof back in sequence?
Do I need to follow the emergency release procedure to get the roof back into position to repeat the sequence?

Why would BMW allow the shell to lock when the deck-lid is not in the closed position?!

Any help would be appreciated.
 
You are talking about the MS on the rear shell (where the rear window resides)?
If so, how can I unlock the roof shells to move them vertical to replace them?
Right now I’m in this position:

0A107D60-C623-482B-ADD1-2EE8CDA808AC.jpeg
 
Careful the boot lid will slowly fall on the roof shells.
I'm surprised if the rear window roof shell is locked with the boot lid open.
But if the boot down switches are faulty, i assume that could happen.

I bought two hall switches 2nd hand from a Renault car breakers, they use the same switches, they were cracked also but worked fine.
Only the casing cracks, the insides were fine as i opened one up. And they worked. Replacing hall switches cures the problem because it's probably the wiring or sockets that are faulty.
 
Are you sure, i thought the rear window shell cylinders over travel to lock, otherwise in accident it could be thrown forward.
Otherwise the shell could be lifted forward, over the top, a two man job.
 
RobbiZ4 said:
flybobbie said:
I bought two hall switches 2nd hand from a Renault car breakers, they use the same switches, they were cracked also but worked fine.
Only the casing cracks, the insides were fine as i opened one up. And they worked. Replacing hall switches cures the problem because it's probably the wiring or sockets that are faulty.
Click to expand...
Did you identify the source of the cracks? Didn't see that in the past! The HS housings are clipped into the hydraulic cylinders and never ever are touched by any mechanics and normally can't be destroyed. How could they get destroyed in your car???? :o
Click to expand...

My hall switches were fine as it turned out it was the salmon relay problem.
But i searched around, just in case for Hall switches and found a breaker advertising a cylinder with hall switches on, same look, wires, etc.
Seems quite common on a range of vehicles, in fact a YouTube poster started my hunt as they are used on Lamborghini.
The switches i bought turned out both to be cracked, but i experimented and found i could get the current to in the hall switch on detection.
And on the vehicle the Foxwell reader showed they were switching.
Why they crack just bad plastic, no load on them.
It might be the aluminium cylinder expands and cracks the casing.
Or the potting compound inside with the magnet expands and cracks the casing.
 

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I've seen some HS with rust inside on the metal, that caracked the cover.
:(
 
Hey guys, thought I'd provide an update in case anyone has a similar issue.
With the rear shell locked in place while the rear module was open I needed to initiate the emergency open procedure using the special BMW roof opening tool ($58 from the dealership). Once un-locked I was able to position the components so that the sequence could continue as normal. The top was still wonky however. Further investigation revealed a fried negative activation line between the #2 relay on the hydraulic pump to the CTM. Inspection of the CTM revealed a blown out pin corresponding to that line.

Step 1 - Replace CTM $150 from ebay
Step 2 - Replace negative supply line with fresh wiring.
Step 3 - Test

Result - Still failed.
Stuck.

Kept pushing on and checking all wiring as I didn't trust the previous owner(s) to solve this correctly. Turns out they connected the hydraulic relays incorrectly with valve 1 and valve 3 inputs reversed. After swapping these to their correct positions and validating all lines tight and working I noticed that the rear luggage light was not illuminating. Turns out my EMF unit (electric parking brake controller) had itself been fried (I think this car was stuck by lightning) which was causing a bad ground. I had already purchased a replacement and installing it led to a fixed ground, working luggage compartment light, and valid responses from all sensors (you can read this out in real time by showing the data-stream from your ODB scanner tool).

Moment of truth for opening and closing....
drum roll....
It worked!

Hooray! Working top, parking brake, no dash lights, and inspection of the datastream reveals all components working in proper sequence and registering their associated states.

Now this might not be for everyone, but having someone face a similar issue would have helped me know where to start. As usual, find something easy to trace that is broken as it could oftentimes lead to the underlying issue being your solution. Fun times indeed. Hopefully this is helpful to anyone venturing into the world of BMW electronics.

JW
 
Success! Glad to hear you fixed it. I spent about 6 months trying to get my passenger heated seat working. Always easy when you know how. I bet you'll be holding your breath every time you open it for the next few weeks though... get back to enjoying the car without the hassle! :thumbsup:
 
jdogg9981 said:
Hooray! Working top, parking brake, no dash lights, and inspection of the datastream reveals all components working in proper sequence and registering their associated states.
Click to expand...

whoa whoa congrats and enjoy!!
 
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