NC928S4

The sunroof has not operated since I got her 18 months ago. The PO had done some interesting caulking work so I decided to clean things up by replacing the seals and ultimately fix the sun roof.

What I've done so far...

1) When I apply battery power directly to the sunroof motor the motor and transmission work as expected in both directions when polarity is alternated.

2) I installed a new sunroof switch.

3) Fuse is good. I popped a couple by trying to jumper the old switch. So there is power at the switch.

4) Manually, opening and closing sunroof by rolling the rubber collar works fine without a lot of resistance.

Pressing the new switch in either position does nothing. Car is running doors closed, car is running door open, car off door open - nothing.

Is there a relay for the sunroof ? Help and thanks.

lonnie77

The same relay that supplies power to your windows (VI) also supplies power to the sunroof through fuse 14. If you have power and ground at the switch (check for both) then you should have power at the motor. There are two connectors between the switch and motor.

Kevin in Atlanta

I am in the same boat. Sunroof worked until I tore apart the console to repair a couple of vacuum pads.

At this point I have power to the switch. I checked the ground at the plug connector and switch - all good.

At the switch if I run my continuity tester from the red to any other solder point there is continuity. That does not seem right. Bad switch?

Tony

Funny...Mine quit the other day as well...fuse is good also.

Kevin in Atlanta

Welcome to the boat.

kevin2012

It may be the power window/sunroof control module under the left side seat. Take a look and see if all the connections are good and tight. Try to borrow another control module from other 928 owner and see. I purchased an used one months ago from eBay to replace mine. Hope this help.

NC928S4

Misery loves company...

I dove back in and have come to realize my multi-meter is a piece of ship. I'm getting inconsistent readings even when I hook it up to a battery.

The switch has 4 leads and I assume that:

BROWN is GROUND
RED is POSITIVE
BLACK -->
| ---> These go to motor?
GREEN -->

I think the switch reverses polarity to open & close since the motor only has 2 leads.

Question: Is this a correct assumption?

I don't think I see a window/roof controller under the drivers seat. Lonnie said the VI relay controls the roof switch.

Question: Does the relay sit between the switch and motor? I think it has to so that it can sense current overload when the roof is fully opened, fully closed or wedged.

I'm buying a "real" multi-meter tomorrow AM but all comments are welcome.

lonnie77

There should be a two wire connector at the motor. Disconnect the motor and check for power when the key is on and pressing the sunroof switch. I did this once and when I reconnected the motor it started working. If you don't have power then you will need to find the other connector (14 conductor) and check for power on pin 6 & 7. If you have power there then it could be a broke wire going to the motor.

kevin2012

Mine is a 1991 S4 and the window/sunroof controller is located under the left seat. Not sure if it is the same for a 89 S4. Base on the following posts, the controller is also located at the same spot for 90 S4model.

https://rennlist.com/forums/928-foru...trol-help.html

https://rennlist.com/forums/928-foru...ing-sound.html

Hope this help. Cheers.

MainePorsche

I had a problem one time where the sunroof wouldn't open or close instantaneously. Went through the diagnostics and it ended up being a screw through the switch wiring harness as it bent around, and behind, the rear center console panel screw. Sunroof didn't fail immediately after the other work under the console. Just something to consider.

Kevin in Atlanta

Popped the switch out. PO's mechanic did some soldering/wire replacement. Connected my continuity test alligator light to the positive solder point. I touched each of other solder points and all them were grounded as they should be. Testing the switch indicates the ground was broken correctly. The motor was silent. So I need to look at the soldering/wiring job the PO did.

NC928S4

Success! I got my new multi-meter and methodically tested voltage at fuse panel then on the plug connector to sunroof switch and then the new switch. Juice was good at all points. Press the switch and it worked.

Damn I didn't do a damn thing other than test for voltages. The only thing I can think of was plugging and unplugging the fuse and or switch connector removed corrosion. Wish I had a better explanation.

To get some satisfaction that I actually did have a bad switch to begin with, I hooked up the old switch and proved in fact that it had failed.

Thanks for everyone's help.