Fitting the rear electric windows is a lot simpler than people think. There are a couple of fiddly bits which I will try and cover in as much detail as possible and of course there are several parts & tools you will need before you commence.
Passenger side rear electric motor assembly
Passenger side rear electric window switch
Passenger side door wiring loom with electric motor and switch connectors
Drivers side rear electric motor assembly
Drivers side rear electric window switch
Drivers side door wiring loom with electric motor and switch connectors
Drivers door switch panel with rear window controls and isolator switch
2 x Small nuts & bolts (approximately 1.5" long with reasonable size head, bolts should be quite thick as they will take a bit of strain)
4 x Pop rivets (rivet head should be 11mm long x 5 mm wide ish)
Short length of spare wire
T20 & T25 Torx bits & driver
Piece of cloth (strong J cloth or duster ideal)
Small straight screwdriver
Drill with about a 7 or 8mm drill bit
Pop Rivet Gun
Multimeter (optional but makes life easier)
Carefully remove the door handle cover with a straight edge (preferably plastic, but if you're careful you can use a screwdriver don't blame me if you scratch it though). Undo the two screws inside and remove them, also undo and remove the two screws at the very bottom of the door panel holding the panel to the door.
Push back on the door trim around the window winder and take your cloth and feed it around the back of the handle with the handle pointing upwards. Make sure the cloth is between the handle and the backing plate for the handle so that it will catch the securing clip, leave some slack in the cloth above the handle. It should look something like the picture below.
Now, pull down reasonably hard with both ends of the cloth, one side or the other (or sometimes both) should catch the clip holding the handle on and pull it off allowing you to remove the handle and leaving you with the below.
You can now remove the door panel completely, pop it off from the bottom upwards, there are two plastic clips on each side that will pop out under pressure, don't be too scared to pull on them. If you break the clips, they're easily and cheaply replaced (Halfords do a pack of 12 for about £1.89). Once you've got the door panel removed, remove the window winder grommet.
Then the lower grommet in the bottom of the door.
Now, very carefully, being careful not to tear it, remove the damp proofing layer on the door (the top corner will probably pull away as for some reason it is perforated, this isn't an issue and doesn't affect the damp proofing of the door, you can see mine did in the below picture as that corner of the damp proofing is still there). Marked on this picture for reference are the five rivets you will need to drill out later on in the process (do NOT do that yet).
Now we need to disconnect the wiring loom to the door, between the door and the car you will see the rubber tube the wiring runs inside connected to the door with a multiplug. Push in the blue clip all the way in and pull the plug out of the housing (this is really simple to do and if you push the clip in far enough will come away easily when pulled).
At this point you can check if your car actually has the wiring in place for the rear electric windows already (to my knowledge, most if not all of the pre-facelift models do, a lot of the facelift models don't). Check in the car end of the loom that you just disconnected, see two large connectors in situ? (as shown in pic below). If so then your car is pre-wired for electric windows in the rear.
You will probably see that the door side of the loom doesn't have both connectors (if it does, you may already have the full loom in place). Mine looked like this, as you can see (arrowed), mine had one of the connectors missing on the door side).
Assuming the car side of your loom has the two connectors as shown above, carefully strip out the wiring loom from the door by popping out the various clips. If your loom doesn't have the wiring as shown, then it's a much bigger job and beyond the scope of this particular howto.
There is one clip (the last one on the run) that is particularly fiddly to get at. You need to push up the red clip as you ease the clip out. Problem is this clip is right at the top of the door just above the lock mechanism. It's fiddly but you can get to it.
Here's that clip once you've removed it.
Here you can see the two different looms together, old at the top, new at the bottom, this shows (badly) the connectors for the motor, the switch and the tweeter (an added bonus if you do this mod is that the wiring is in the loom for the tweeter).
Now put the winder handle back on and wind the window down until you can see the double sided plastic rivet that connects the glass to the mechanism through the small access hole.
Using a screwdriver a few mm wide carefully open up the clips inside the rivet. Be very careful, this is a double sided plastic rivet, one part fits from each side of the mechanism and they clip together. When you ease the screwdriver in it will (with a little fiddling) release the clips holding the two parts together.
Carefully prise the two parts apart whilst holding the screwdriver in place, the clips should come apart reasonably easily. Retrieve both parts. This is what the plastic rivet looks like once seperated and out of the door.
Wind the window right back up to the top and tape the glass over the top of the door to prevent it falling when you remove the mechanism (from experience, they're actually quite tight anyway and are unlikely to fall, but better safe than sorry). Then drill out the five rivets indicated in the earlier picture. Use a drill bit that's wider than the hole in the rivet and it will drill the head off in seconds.
Ease the mechanism out of it's locators, it should come away quite easily.
Then feed the mechanism out of the main access hole at the top of the door.
Now, the fun bit, the motor I'd bought second hand had been raised right to the top when removed and was too high to be able to fit straight in as there was not enough play between the top and the glass to position it. I needed to lower it slightly, luckily in my case the main power to the door is there already, this will probably be the case (you can easily check the two big connectors on the wiring loom with a multimeter), but if not then it should only be a case of fitting fuses in the fusebox. The switch wires to make the window move up and down aren't enabled until it's been tech2'd, as that's controlled by the door control module. So plug in the loom to the motor and leave the motor hanging.
CAREFULLY strip back some of the insulation round that part of the loom.
And VERY CAREFULLY pierce the insulation on the red, the blue/red and the green/grey wires using a very sharp knife (be careful not to damage the actual wires inside too much).
Then using a short piece of spare wire, carefully short the red wire to the blue/red one and the motor will lower. This can seem quite sudden, remain composed, I do not take responsibility for any part of this and if the motor jumps up and hits you in the knackers it's your own fault
Lower the motor enough to be able to fit it into the door, then unplug the loom again and make sure the wires that are pierced don't touch anything (you'll need them again in a bit so don't fully insulate them yet). Fit the mechanism into place, making sure you line the glass up correctly with the top plastic fitting and locate the two locating pins top and bottom correctly in the door. Next pic shows the motor in place, the lower locating pin below it (arrowed) and the hole to rivet it on with below that (arrowed).
And the top locating pin (arrowed) with the rivet hole above it (arrowed), both just above the access point for fitting the plastic rivet.
Load your rivet gun
And carefully pop rivet the two holes to attach the mechanism to the door. This literally takes two hard squeezes on the rivet gun and is done in seconds.
Then fit the stabiliser bolt through the extra hole in the mechanism and the door (I just bought a couple of standard short bolts with nuts from Halfords for about 50p).
Tighten the bolt up and then refit the wiring loom to the motor, again using your little spare bit of wire and supporting the glass while you move it (short blue/red to red to lower window or grey/green to red to raise window), position the motor and window so that you can see the plastic rivet point through the small access hole.
Carefully refit the two parts of the plastic rivet one from each side and make sure they clip together correctly and everything lines up properly. You can then use your wire again to give the window a full test top to bottom and back up again to ensure you have done it all right and left enough clearance for everything.
Once done, raise the window to the very closed position, this is the last time you can use it until the tech2 has been done. Wrap each individual wire you split securely with strips of insulation tape and then once each is done individually, wrap a final layer round the whole lot to repair the loom insulation.
Refit all the bits removed from the door.
Carefully refit the damp proofing layer using spray adhesive, be careful to line up any holes that need to be lined up for the panel clips.
Refit the speaker and then fit the door panel back on, remember to reconnect the door opening handle or your passengers won't be able to open the door from the inside. Replace any broken panel clips and pop the panel back into place.
Connect your new switch (and tweeter if you bought the ones with tweeters in, a bonus of this mod is you get the rear tweeters connected if you didn't before). Fit the switch in place, replace your handle cover and stand back and admire your work.
Repeat the process for the other side. Your rear electrics are now fully fitted (and tested) book the car in for a tech2 session to enable them (don't forget to take your "car pass" along because they need the security code from it to tech2 it).
You can buy a couple of blanking plates to cover the old holes left by the winders, fit the replacement drivers door switch and it's complete. Enjoy your new rear electric windows.