I have searched the archives and found lots of related info that was helpful getting this far but I have some sunroof issues I need help with. 2007 S600 W221 with pano roof. Rear sunshade works fine.

Recently the front sunshade started requiring multiple push and holds of the switch to get it to fully retract. About four to full open. Once full open the sunroof will not do anything. On closure the shade will continue to close if you hold the switch but once closed does not know it is as evidenced by the infamous machine gun chatter of the gear.

I dropped the headliner and verified it was the shade motor chattering. It was only when it tried to continue closing against an already closed shade that it flexed enough to cause the gear slip and chatter. I did the “washer on the rubber mount points” for both motors and that fixed it well enough to stop the flex and chatter but did nothing for the overall problem.

My indy shop does not do sunroof work but was kind enough to put his more sophisticated reader on it and says it is showing a hall switch failure. I assume that is as in Hall Effect used as a position sensor. Other writeups imply the motors have an internal rotation counter that the system uses to indicate position?

I bench tested both motors and they run fine when 12VDC is applied directly. But plugged in the shade motor does the step / stop, step / stop routine in the open direction. I was able to fully raise and open and close the sunroof manually using the emergency drive access on that motor.

So; I suspect that what I am looking at it a bad position sensor? The questions I have are:

1. Can anyone confirm the position of the shade and / or sunroof are sensed by a sensor internal to the motors?

2. Can anyone confirm the sunroof must “see” the shade fully open before the system send it power?

3. Does anyone have access to a control or wiring diagram for this system?

4. Does anyone know if the switch is “smart” or just electrical?

My gut tells me the problem is with the motor that sort of works, the shade motor. The fact it steps, steps, steps makes me think a sensor is telling it to stop. I think the sunroof motor would work but is not getting any power since the system does not see the shade as full open? Anyone know? I would like to avoid buying both motors if not necessary.

 

Have you tried MB diagnostics normalize procedure to reset.

 

Yes, thank you for the links but that was when the "hall sensor failure" code appeared.

 

I know they say the definition of insanity is trying the same thing and expecting different results but I've also learned that often when resetting maintenance reminders you have to try several times for it to "take". Well I got in the S600 today and thought what the heck, I'm going to try the sunroof switch reset sequence once more even though it hasn't helped the last several times I did it. Up, back, forward, down for 5 seconds in each position and I'll be darned, it reset and everything is back to normal function!