Modification: Dual Auto Down Power Windows 850

[PCars]

Last weekend, I felt like doing a modification to my 850. Not a big one. Just adding the automatic down function to the passenger window. I always felt kinda silly tapping the button for drivers then having to hold the button for passenger, just to get both windows down on a hot day. It involved removing the center console and window switch with harness from my car and then grabbing one from a junkyard car as well. The harness has a relay attached to it that mounts near the ebrake handle. That is the auto down relay that clicks off power when the window is fully down. I spliced in another relay for the passenger switch and now have dual auto down windows. It works great and only cost like $20 for parts. I will do a write up if enough people are interested. It was not very difficult and is a very convenient, not to mention cheap, addition.

[anjill182]

Yes. Write it up! Thanks.

[jblackburn]

Yes please!

My windows are incredibly slow; I hate having to hold the button for it too!

[precopster]

Make that three!! I LOOVE that feature.

[ojdorson]

Four! I want to add auto-down to the passenger window, too!

I also want to add it to both windows in my 75 164E, eventually.

[kcodyjr]

Five and six. If you want the bonus brownie points, dig up the part number for that relay so we can avoid dumpster diving at the junkyard, and please do post details of where exactly to splice it in. Thanks!

[PCars]

Okay, sorry about the wait. Here's the write up. This is for an 850 window switch. I did figure out how to do it for S/V 70s (Jblackburn's) but it is a little different. Scroll down to the bottom for S/V 70 otherwise follow next step for 850.
What you'll need....
-Torx 25, Torx 20, or Torx 15 (depending on your setup)
-8mm socket (sometimes required)
-Soldering Iron
-Electrical Tape
-Pocket Screwdriver
-Small pick or prying tool
-Auto Down Relay w/ connectors or window switch assembly (from salvage yard)


Remove the center console from the vehicle.

On the underside, remove the mirror connectors from the window switch, brass looking clips from the console to free the harness(grey connector), and the relay from the armrest cavity.

Once you have the harness separated from the console, go to a junkyard (pick your part type place) and grab that same harness and switch. Mine was about $20 bucks, included the auto down relay, switch and harness. Not that you need the switch but it could come in handy later on. It you don't want to brave the salvage yards, the part number for the relay is 68 48 215. You'll have to get some additional connections and wiring to make it work though. This is the wiring diagram for the relay that controls the auto down function for the drivers window. K/1 is the relay.

Going into the relay...
Pin #1: "Y" Yellow wire (the signal to the relay to auto down but it also provides power through an unenergized relay when rolling the window down normally)
Pin #2: "GN" Green Wire (Provides power to lower the window, during this operation this circuit is grounded by the Blue/Green wire)
Pin #3: "BL" Blue wire (Power Supply from relay 2/60, this wire is spliced into another blue wire coming from the grey connector. This blue wire provides power to all window functions)
Pin # 5: "SB" Black Wire ( Ground wire, spliced into existing ground wire from grey connector)
We are going to mimic the "stock" driver's auto down wiring on the passenger side window switch. There is no difference in window switch design and the circuitry is already protected by relay and fuse. This addition will not cause any electrical problems or overload any circuits, the system is designed to handle more than one window operating at the same time.

Locate the Blue and Black wires off the relay(salvage or bought), Pins 3 and 5 respectively. These need to be soldered onto the switch where the other blue and black wires are soldered into the plates or spliced into the wiring somehow. They just need to be connected in parallel with these circuits. If you look at the picture below, you can see where I soldered the blue wire onto the supply plate(to the right of the two yellow soldered connections) that had the existing blue wire on it(to the immediate right of the right/white wire.) Basically, just make sure that blue is connected with blue and black is connected to black.
Next, locate the white wire coming out the bottom of your passenger window switch. This needs to be connected to pin #1 on the relay(yellow wire). You can use a butt connector or (if you grabbed a salvage switch assembly) unsolder the yellow wire and disconnect it from the salvage driver's switch. Do the same for the white wire on your pass switch, then heat up the connection on your pass switch again and place the yellow wire(from the salvage relay harness) into the slot where the white wire used to be. It will look like this.

Note: The two yellow wires coming from the drivers and passengers switches on the down circuit.

Note: The two black wires from both relays are connected to a common ground plate.

Passenger window switch wires before removal.

Now you have to replace the power wire coming out of the relay. If you got the parts form a salvage yard, the easier way to do this is to remove the cover from the even side of the grey connector on both harnesses(you'll see the numbers 2 4 6 8 10 12 14, pry this tab back). Find the white wire on your harness (pin 4) and pry up on the wire's connector tab inside to release the terminal. Remove the white wire completely from that grey conector. pry up the tab for the solid green wire(pin 2) on the salvage harness, bend back the tab and reinsert the green wire from the salvage relay into your harness(grey connector) on pin 4. You should have a green wire on pin 2 from driver's relay and a green wire on pin 4 from passengers relay when done. Make sure both terminals are secure in the connector and snap the cover back into place.

The connector on the right shows where the white wire used to be(pin 4). The left shows both green wires (pins 2 and 4), the new dual relay setup.

If you got your relay online this could also be accomplished by simply connecting pin 2 of the relay with the white wire of the switch with a butt connector going back to the grey connector on pin 4.
Basically, these items must be correct in order for this to work. The blue and black (pins 3 and 5 off the relay) wires must be connected to power and ground respectively. The yellow wire (pin 1 off relay should be connected to the the passenger switch where the white wire used to be. Pin 2 (green wire)off the relay should be connected to the white wire going back to the grey connector on pin 4 (if you swapped wires with a salvage piece, this will be a green wire at this point).
This setup seems to be more complicated than it actually is but I just want to make sure we have it right.
Install the grey connector and new relay/switch setup into your car and test. If all good, merge the two relays together. There will be just enough space for the two of them. I used electrical tape to secure them.

Dual Auto Down Relays

After the test, reinstall the switch, relays and harness. Reinstall the console and retest. Thats it for 850s installation.

For S/V 70, I took a look at the wiring diagrams. It looks like the relay for auto down is integrated into the main window switch on the drivers side. If I remember correctly, there is a click feature on those switches also that indicates when the auto down function occurs. You will not have this for the passenger but there seems to be way to splice in an 850 auto down relay. This is only hypothetical but should work the same as for 850. Remove the front passenger door panel. Find the connector for the window switch. In a 1998, power is provided on pin A1 of the connector(Blue Wire). The window motor is controlled by pins 3 and 2, white and Blue/White respectively. After getting that 850 relay (part number above), splice the Blue wire(pin 3 off relay) with the blue wire on pin 1 of the passenger window switch (borrowing supplied power). Connect the yellow wire or Pin 1 of the relay to Pin 3 off the switch(white wire). Connect the other end of the white wire(going out of the door (pin 22 on A pillar connector)) to pin 2(green wire) of the relay. Connect pin 5 (black wire) to a ground somewhere in the door. Hopefully this allows auto down of the passenger window for you. Unfortunately, I don't have a S/V70 to test this on, but it looks like a very similar circuit. Good luck! I tried to explain as much as possible without seeming longwinded. Cheers!

PS: Upon showing this to a friend, he commented "It isn't auto up also!" I paused for a few seconds until I realized that I would need 2 more relays spliced in to do auto up also. 8 relays in total, if I wanted to do all 4 windows up and down! Haha

[vjaneczko]

Sweet! I'll have to add this to my summer ToDo list!

[jblackburn]

Awesome, thank you!

I have added this to the repair database; you'll also get MVS Contributor status!

I'll have to try this out at some point - and it gives me an excuse to go poke around at junkyards!

[PCars]

No problem. Hope you guys all have success.