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93 300E 2.8
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101 Posts
Discussion Starter #1
So I tilted my sunroof up today and it wouldn't go back down. It made a slight noise like the motor was trying, but nothing moved.

When I got home I fiddled with it a bit, and eventually got it to tilt back down with the emergency drive.

However, while I was fiddling with it the motor stopped making noise when I activated the switch. I took the switch out and tested it for continuity, and it seemed to make enough connections for the motor to work.

I'd like to power the motor directly and see if it is the culprit, or perhaps the sunroof relay. Any clue as to how to power the motor directly from the battery?
 

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93 300E 2.8
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101 Posts
Discussion Starter #2
Thought you guys might want an update. I completely removed the sunroof motor and tested it by bypassing the relay, it spun just fine. I also checked the sunroof cable to see if it was binding in any way, and it wasn't. The sunroof itself also slid back and forth easily. Based on this info I have to assume the sunroof relay was bad. I also surmised that although the motor worked with no load, it was weak and drawing too much current, which probably lead to the relay failure. My reasoning for this was the sunroof would get stuck when opening and closing it, and frequently required a bit of assist, either in the form of manually helping the sunroof or bumping the switch repetitively so it would get past the sticky spot.

So I decided to install a used sunroof motor assembly. This turned out to be easier than I thought. The sunroof now opens and shuts easily with no binding. A side benefit is I aligned the cable with the switch, which means my switch now operates logically (the up/down function is now aligned with the roof being shut, so up and down now actually move the roof up and down, as opposed to the crazy manner in which it used to operate, which was moving the switch either up, down, or back would all cause the roof to move either down or back, depending on position, and pressing forward would move the sunroof forwards or up.)
 

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Premium Member
Current, 90 300CE, 92 400E (Sold 95 E320,70 250C, 91 190 2.6, 91 420 SEL, 95 300D, 87 TD)
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1,702 Posts
Sunroofs can be a bigger job (believe me I re-built mine from the inside of the car..dropped it down replaced the "L" brackets) . I'm glad yours was just a motor.... much easier!
 

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93 300E 2.8
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101 Posts
Discussion Starter #4
When it got stuck I was expecting the job to be much worse, believe me, I was very happy it was just the motor.
 

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Registered
1983 300 sd
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41 Posts
How did you get the sunroof motor back in? I have a300e 1986, it was hard to get out and I don't want to tear it up getting it back in. Specifically, how did you feed the cable back in the motor? Thanks in advance,
 

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Registered
1983 300SD, 1986 560SEL, 1992 300D, 1995 E320 Wagon
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298 Posts
Thought you guys might want an update. I completely removed the sunroof motor and tested it by bypassing the relay, it spun just fine. I also checked the sunroof cable to see if it was binding in any way, and it wasn't. The sunroof itself also slid back and forth easily. Based on this info I have to assume the sunroof relay was bad. I also surmised that although the motor worked with no load, it was weak and drawing too much current, which probably lead to the relay failure. My reasoning for this was the sunroof would get stuck when opening and closing it, and frequently required a bit of assist, either in the form of manually helping the sunroof or bumping the switch repetitively so it would get past the sticky spot.

So I decided to install a used sunroof motor assembly. This turned out to be easier than I thought. The sunroof now opens and shuts easily with no binding. A side benefit is I aligned the cable with the switch, which means my switch now operates logically (the up/down function is now aligned with the roof being shut, so up and down now actually move the roof up and down, as opposed to the crazy manner in which it used to operate, which was moving the switch either up, down, or back would all cause the roof to move either down or back, depending on position, and pressing forward would move the sunroof forwards or up.)
George, how did you power the motor directly?
Which pins?
 
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