Sunroof Switch Replacement (or re-sync)?

[Ntrepid]

Hi -

I have a 1993 500E which has an issue with the tilting sunroof. The sunroof will tilt up and open properly using the sunroof switch and pushing up or back respectively.

However, if I want to close the sunroof, pulling the switch down (from the tilt position) or pushing forward (from the open position), does not work. This means I have to use one of the other options on the switch to get it to close and then stop once the sunroof returns to the closed position.

I've heard of re-syncing the sunroof by opening it in the tilt position and then holding the button in the up position for 3+ seconds but this does not work. Am I doing it wrong?

If this won't solve the issue, I also have a replacement switch and I wanted to ask how the one it replaces is removed.

Thanks in advance.


Robert

 

[gsxr]

Sounds like either a flaky switch, or a flaky relay on the motor unit. Do you have access to spare parts to swap out as an experiment?

For the record - I've never encountered a bad switch, but I've had to replace the relay module on the motor unit on several of my cars.

 

[500AMM]

Hi -

I have a 1993 500E which has an issue with the tilting sunroof. The sunroof will tilt up and open properly using the sunroof switch and pushing up or back respectively.

However, if I want to close the sunroof, pulling the switch down (from the tilt position) or pushing forward (from the open position), does not work. This means I have to use one of the other options on the switch to get it to close and then stop once the sunroof returns to the closed position.

I've heard of re-syncing the sunroof by opening it in the tilt position and then holding the button in the up position for 3+ seconds but this does not work. Am I doing it wrong?
If this won't solve the issue, I also have a replacement switch and I wanted to ask how the one it replaces is removed.

Thanks in advance.

Robert

Mmmnnn - I don't think our sunroof function is "that smart" so to say, AFAIK it's a simple el.operated mechanical system. It could be a relay as Dave mentioned or a switch malfunction - which rarely happens though. But you can add some thin oil inside the switch and massage it, just like the seat headrest switch needs sometime. It's also rarely something wrong with el.motor and feeding wire, so you likely sit back with a mechanical issue. Slide the sunroof fully open and check for any broken parts on the linkage, if they looks OK it's likely an alignment issue.

I guess it is a written procedure for the sunroof alignment, but in lack of that I managed fine on my first MB, 300TDT, back in 1999. After visiting the MB shop and was told how extremely difficult this was, I went home to study this in peace. The only adjustment is the carriers position on the hatch, and the feeding wire position from the el.motor. Everything is in fact a simple mechanism, but the carriers are made of cast aluminium and can break over time, wear out, or they are clogged of old grease & dirt.

• run the sunroof to open position to access the clips holding the trim
• stay inside the car on your knees in each seat
• you split the clip with a long flat screwdriver and slide the trim out
• then close the sunroof fully
• loosen the bolts holding the hatch to the carriers, just slightly so the carriers moves freely by hand
• checked that the hatch is resting entirely in locked position
• jog the el.motor a little back and forth to see the mechanism isn't jammed
• (if you unbolt the carriers fully and drive the el.motor, they may move individually because the hatch is in fact bridging them in correct position)
• find the best fit in middle position around the bolts, and tighten the carrier to the hatch again
• then mark with a felt pen around the carriers to have a position reference
• test operate the sunroof in all positions
• if it doesn't close/open evenly, close the sunrooof again
• then readjust the carriers position based on the reference marking you did
• the needed adjustment is small, maybe 1-2 millimeters in either direction
• DO NEVER adjust the carriers when the sunroof is in any open position

So, that's how I managed this extremely difficult job. Bring along good coffee, nice music, and no kids & woman around, then you're done.

 

[Ntrepid]

Thanks to you both for the quick response. I have a spare switch I am willing to try (first). How do I remove the switch?


Robert

 

[500AMM]

Thanks to you both for the quick response. I have a spare switch I am willing to try (first). How do I remove the switch?

Robert

You have to pop out the interior/dome light assembly to access the switch. Insert a flat screwdriver on the passenger side (right side) of the dome light, as there is the springs holding it in place. The driver side has the tabs, so if you try to remove from that side you'll rip the headliner a bit or break the tabs. Then pry the light assy straight out from the headliner, it doesn't fall down but will be hanging in the wires.

Then you'll find the hooks holding the switch in place.

 

[Ntrepid]

Great! Thank you. Mission accepted. I'll tackle this tonight.

 

[silveralfa]

I have had timing problems with the sunroof with symptoms like yours. I have also had a bad relay. I have never seen a bad switch. I hate to suggest this but mercedes source has a series of pay view videos which I watched that helped me immensely. The price was not excessive in the scheme of things and I have 3 w124s with tilting roofs. I followed along and cleaned and lubed the roofs but my worst problem so far was a roof out of time. Timing is purely mechanical and is done at the motor not with the switch. Now all is well, both roofs I have done so far work great

 

[Ntrepid]

I have had timing problems with the sunroof with symptoms like yours. I have also had a bad relay. I have never seen a bad switch. I hate to suggest this but mercedes source has a series of pay view videos which I watched that helped me immensely. The price was not excessive in the scheme of things and I have 3 w124s with tilting roofs. I followed along and cleaned and lubed the roofs but my worst problem so far was a roof out of time. Timing is purely mechanical and is done at the motor not with the switch. Now all is well, both roofs I have done so far work great

I have seen the MercedesSource videos on YouTube and wondered if they are of value to purchase. Thanks for letting me know. My next step after trying the switch (since I have a spare) will be cleaning the roof and re-lubricating.


Robert

 

[gerryvz]

I believe that GSXR served as technical adviser on those MercedesSource sunroof maintenance videos.

 

[clarkz71]

I believe that GSXR served as technical adviser on those MercedesSource sunroof maintenance videos.

Yes, but you know that being in business with family never works out.

 

[Ntrepid]

I can now confirm the switch *is not* the issue. On to the relay.


Robert