91’ 850i Sunroof not working

[Wcsco123]

Hello again!

Looking for tips on what to check for while repairing the sunroof…
I have taken the headliner out for reupholstering and might as well try to tackle the sunroof while its out.

I have tried actuating the sunroof manually with the allen key in the toolkit.
It opens, closes and tilts without issue. No crunching, grinding or misalignment.
Checked all fuses. None related to the sunroof burnt out.
When using the switch the motor does not get any voltage.

Any info appreciated!

[rjjablo]

Are you getting any power at the switch?

If you are its the switch

Have you have the capacitors in the General Module Changed? Causes all kinds of problems in the interior

[Wcsco123]

Capacitors likely haven't been changed on the General Module. When I get a chance I will have a look and see!
Ill check for 12v at the switch too. Im sure it will be something silly I’m overlooking.

[henryc]

Wcsco123- Getting power to the switch is the first thing to check. In our local group of E31s (BC8s in Vancouver Canada) we have seen a lot of sunroof issues. Two of the most common- the plastic bits of the sunroof components crack with age and the panel will not function electrically. Replace all, not just the cracked pieces, of those items if any are found faulty. Second, the headliner material has been replaced by a trim shop with thicker material than fitted by the factory. This thicker material gets fitted to the interior sunroof panel and the thickness is too much for the sunroof to function electrically. You may want to check with your trim shop about the upholstery thickness they are using on your inner panel. Too thick a material will be a problem! In both cases, we found that you could still open and close the sunroof manually using the tool from the tool kit or a 1/4" drive ratchet with the correct sized allen socket.
If you decide to replace the sunroof plastic components, here is an excellent guide: http://www.frankies-bmw.com/8series/...es_sunroof.php

Hope this has been helpful! / Henry

[smc850ci]

My plastic bits were broken, cracked, and generally bent. I was able to source the parts and just finished installing them yesterday. The sunroof now works great! I did the headliner myself, and after experiencing the binding issue with the thicker material, I went with different material with not foam backing for the panel

[Albert850i]

There is no power at the switch as this switches mass not plus.

[smc850ci]

There is no power at the switch as this switches mass not plus.

Not sure what you mean by 'switches mass not plus.' ? But if there is no power to the switch, you will have to look farther up stream.. you also said the fuses were ok? Did you remove the fuse and then reinsert it? Sometimes the blades of the fuse just need to be cleaned or reseated. Same with the relay, did you check that and if so, did you pull it and reseat it? Next would be the wiring harness, check for continuity from the relay to the switch, and from the fuse to the switch.

Do you have a copy of the wiring schematics? That will help finding the correct relay, fuse, and wires.

[Albert850i]

There is no plus at the switch, just earth signals.

[Wcsco123]

Still having issues after swapping in known working switches, sunroof module etc.
Voltage at the switch for sure.
I was checking the wiring and found that the small blue/red wire going to the module shows 12v and The red/brown large wire only shows 4v when the car is turned on.
The small red/blue is always hot. The larger red/brown is controlled by the power protection relay #1.
I ended up testing those relays with the car fully powered up and off and they do not click at all when removed and inserted from the socket. I then removed them and checked function with a 9v battery. They do work, just not when in the car.
These relays look to be controlled by the GM according to the wiring diagram. Is it time to replace the capacitors in the GM or would there be something triggering it to de energize those protection relays?

[Wcsco123]

Solved!

Wuffer lent me a spare general module to try which solved the issue.
I did check my general module and it looks like someone has replaced the capacitors already, but only 1 matches the exact specifications of the originals. All of them are the correct uF rating, but the voltages are different. Also they are all radial type (both leads on the bottom) if that makes a difference.
Out of interest I will replace them all with exact match capacitors and see if this fixes the issue before relegating it to the N.F.G. box