Hi

I added to my 850 additional Auto relays (7 to be more exactly ) in order to have the Auto Up / Down function on all windows.
What you need is per direction 1 relay. The relays which work are from 850, 960 and S/V40 first generation.

The relay have 4 contacts and it is always a good ideea to get them together with the socket.
The socket (original) has 4 wires which are:
- blue is power supply which is present when the key is turned in Pos I
- black is ground
- yellow is the input which triggers the relay
- green is output and actuates the motor.

There are 2 ways of doing the "mod": the "quick & dirty way" which involves soldering the relay after the command unit.
The "nice" way is done by making a small cable harness which inserts between the connector of the control unit and the car harness.
I'll present the "quick & dirty" first

You need to take out the center console which is a easy job.Now that you have exposed the harness from the control unit do the following:
Auto Down passenger side
- cut the red-black cable . The end which comes out from the control unit is to be connected with the yellow (Input) of the relay.
- The second end to the green (output) of the relay.
- Blue and black from the relay (power supply) to the blue and black cable together.

Auto Up driver side
Same drill as by passenger side Auto Down the used cable is Blue-Green

Auto Up passenger side
Use the Green-Grey cable.

Take care to isolate properly the cables!!!

Back doors
The back doors need to be modified at the door. So take down the door panels.
-Connect the blue (power supply from relay) with the Grey-Red cable from the window harness
-For Auto Up use the Green cable similarly to the front doors
-For Auto Down use the Red-White cable.
- Connect the black (ground) cable to one of the screws which hold the whole window assembly.

The back doors will operate in Auto Mode as long as the On/Off switch in the center console is set to On. If you kill the power in the back by flipping the switch to Off the windows will still operate from the center console but without the Auto functionality.

The "nice" solution for the front
I made a small harness (30 cm long) with 3 standard relay sockets. The harness is inserted between the grey connectors below the ashtray.

This way you do not have to cut and solder any wire. The parts are extremely cheap you only need from the dealer the 2 14pole connectors 968410 si 968411. They are only available in black but this is no tragedy, you only need to cut off the matching plastic pin "the key" so that they plug in each other. The crimp connectors can be bought from ebay for about 2€ 10 pcs.

 

And pictures package II

 

Next package of pics

 

Now to the illumination of the rear door switches.

Volvo used the same switches illuminated in the 960. So if you get your hands on the 960 switches (rear) they fit plug & pray
This is however no real sollution as these switches are pretty rare. A much more feasible sollution is to use a control unit from the 850 and solder the LED from it and use the switch button which has the window symbol on it.
So after you get a control unit carefully take it apart. Watch out the plastic is pretty sensitive !
The LED from the original unit can be cut off and resoldered into your back switch. Take care not to lose the inner parts as they are pretty small. Solder the LED like in the pic.
Reassemble the switch and you are good to go.
I really cannot understand Volvo the 850 switch has even the support for the LED...it's actually only missing the LED

Some advice from a father
The relays cut the power only when they sense a big power drained when the window hits an obstacle. Problem is that with the bare hands I was not able to stop the window ... so I would think twice if you want to have Auto Up in the back with the kids!!!

Happy crafting
Cristian

 

Cool! I'm going to try adding auto up on the driver's window. Thanks for the great post