View Full Version : Wiring MK4 sunroof switch into PFL A4 help

02-08-2016, 02:45 PM
Ive been buying pieces over the last few weeks to change my upper interior to black. The one piece I bought that I dont believe anyone has done was a black sunroof/dome light assembly from an MK4 R32 to wire into an A4. Upon close look the assemblies look like the same shape, but theyre not. The A4 headliner is going to need modified before the assembly can fit, which I havent done yet. The main thing I noticed is the difference in how the assemblies are wired. The pre facelift A4 has 3 wires going to the switch, where as the MK4 assembly has 5. Doing a bit of searching, the MK4's have the central convenience where the sunroof supposedly opens with the key fob and thats where 2 of the wires run to. Ive included the diagrams of both switches, just hoping someone can make sense of what wires I need to splice together.

A4 pre facelift wiring


MK4 R32 wiring


Pictures of the assemblies



02-08-2016, 05:12 PM
From the diagram, there appears to be a sort of fundamental difference.

**Let's just take a pause here to mention that I am not a mechanic. I am not an electrical engineer. And I have never in my life even touched a MK4 R32 sunroof control knob. In my life....Ever. Okay? Okay.

Based on the diagram, it appears the A4 control dial operates solely on resistance. From all the way open, to closed, to tilt - it's just a single potentiometer that controls it. The MK4 dial appears to have a potentiometer - ostensibly to control the open and closing of the roof panel - and a separate 3 position switch. My guess is to control the tilt up and down functions. I believe this is how the Facelift switches work. The slide and tilt are separate switches.

Now looking at your MK4 switch, I don't really see how that makes sense. I would wonder if your MK4 diagram is accurately depicting the switch you actually have there. To me, it looks more similar to the A4 switch - All Potentiometer. All positions, including tilt, being derived from the clock position (and thus the resistance) of the potentiometer. Again, having not touched them, it's hard to say. I can't even see how many pins you have there.

Really, it doesn't much matter how it was supposed to work in the Volkswagen. The only thing you care about is if it will work for you in your A4. My suggestion would be to measure the resistance values of both switches. See if they give approximately the same readings at the same positions. Seeing if the resistance matches for the closed position would be an important one to test. Then fully open, then fully tilted. You get the picture. Indeed, even if both switches had the same 3 pins and even shared the same connector - you would still want to check this. The pray and plug can sometimes end badly.

02-08-2016, 06:26 PM
The MK4 switch has 6 pins on the back of the dial itself and the A4 switch has 4 pins but only 3 are used. I need to get the 6 pin connector and wires for the MK4 switch. I can pull the switches apart and get pictures if that helps.

02-08-2016, 07:46 PM
Ok, so I think you'll be grabbing 3 pins out of the connector, and just not using the other 2. You just have to make sure the resistance values are the same throughout the range of the dials. Get Joe Meetah and check it out.

Wrath And Tears
02-08-2016, 09:38 PM
Get Joe Meetah and check it out.
Joe sounds like a pretty cool guy if he can do that.

02-08-2016, 10:40 PM
Indeed, Joe is pretty cool. Sometimes he can be a little hard to read, but he is always willing to help.

02-19-2016, 01:27 PM
Ok, so I think you'll be grabbing 3 pins out of the connector, and just not using the other 2. You just have to make sure the resistance values are the same throughout the range of the dials. Get Joe Meetah and check it out.

I got the control wired up today. The wiring harness to the control is hardwired into the motor, so I jumped on ebay and grabbed one for $15 a few days ago. I called up Joe Meetah and found a diy online to check the resistance on the potentiometer since Ive never done so before. I think I thought too hard on the process and put in more work than what it actually took. I started with one wire as a ground, testing the others as positive while moving the switch, and done so with every wire. There were 2 wires that I got no reading from at all, so I ruled them out. Ill post a pic that I took of all the info I wrote down, sorry if its sloppy, I was trying to work quick.


Ended up pairing the green wire from the A4 switch to the grey wire for the R32 (Im using these as the grounds), red/yellow wire from A4 to white wire on R32 and then yellow wire from A4 to brown wire on R32. The 2 opening settings on the sunroof work great, but when I put the switch in the center to close, the back is still open. If I move the switch one position towards letting airflow in, the sunroof will fully close.

This is with the switch in the closed position


The position the switch is in to fully close the sunroof


02-21-2016, 03:35 PM
Ended up messing around with the wiring a bit more earlier today, and the method I done above was the only way I got it to work. I dont know how many trips I made out to the car after switching the wires around and not getting anything correct. I believe I can deal with having the switch one click past the closed position for it to actually close. Just like I mentioned above I paired the following wires together to get it to work....

Pin 1 (Yellow/Red) on the A4 connector to Pin 1 (White) on the R32 connector
Pin 2 (Green) on the A4 connector to Pin 3 (Grey) on the R32 connector
Pin 4 (Yellow) on the A4 connector to Pin 2 (Green) on the R32 Connector

This resulted on the Brown, Blue and Violet wires on the R32 connector not being used.

A4 connector to the sunroof motor


R32 connector from the sunroof control to A4 sunroof motor


Finished harness. I probably should have trimmed it down some, but oh well.