E46 wagon folding mirrors (non-M3)
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A number of people have asked me about this, so I figured I'd post some details. This isn't a full DIY as I didn't take pictures while the car was apart, and it isn't for the faint of heart anyway.
All that is needed are 3 parts available at your BMW dealer (left mirror assembly, right mirror assembly, and switch). No painting is needed - you re-use your old mirror housings.
Here is a PDF file
http://www.tmk.com/transient/folding-mirrors.pdf of the ETK page for the mirrors. This will give you the part numbers for the left and right mirrors (item #2) for cars with and without "high gloss shadow line". You also need a replacement mirror control switch. On my car it was 61 31 6 901 383 which is the switch for folding mirrors and seat memory. Part number 61 31 8 373 732 is for folding mirrors without seat memory. The mirror housings list for about $250 each and the switch for about $50.
Before I started I made sure that I had a fuse in position 57 (folding mirrors).
You'll want to disconnect the battery, as the doors have airbags in them and you don't want any accidents. Roll down both the driver and passenger side front windows first.
These instructions are for cars with the HK option - some steps will likely be different for non-HK cars.
I would also suggest leaving one door untouched while you do the other one - you will run into a bunch of "how the heck does this go back together" situations, and having another door for comparison is very useful.
First, I removed the mirror glass (see the split mirror DIY for instructions). Once the glass was removed, 4 small tabs are visible near the corners of the housing. Gently releasing these tabs (they can easily break, particularly the one that is recessed more than the others) will let you remove the painted cover from the leading edge of the mirror housing. What you have left is the part you will replace.
You now have to pretty much gut the doors - remove the mirror switch by pulling up and disconnecting the cable (driver's side) or the blank trim piece (passenger's side) and 2 plastic caps on the underside of the armrest. Unscrew the 3 Torx screws exposed by this. Gently remove the wood or plastic trim, starting at the rear edge of the door and working toward the handle. Remove the Torx screws you have exposed (the one that is longer is the one closest to the handle).
Gently pop the door liner off the door frame. It is secured by a large number of round clips around the side and bottom edges of the door frame and a number of rectangular clips at the top edge of the door frame. Carefully lift it over the door locking pin at the rear. At this point it will still be attached via the handle linkage and a speaker wire. Carefully undo the clip at the rear of the handle and pivot out the linkage cable and white plastic piece.
The speaker wire is attached by a push-in clamp, and then connectors on the backs of the speakers. The woofer is easy - just pinch the clip to release. The midrange is the usual AMP captive-catch connector. I used my usual trick of pushing on the captive catch with a dental pick to depress it, and then pulling the connector halves apart. I haven't found a good way to remove the cable clamp from the back of the door liner other than by giving it a good yank.
At this point you can set the door liner aside. Take a look at the door frame and the general vicinity. If you see any thin felt rings, take them and put them back on the catch pins on the door liner.
You now have to remove a piece of plastic trim which runs from the bottom front edge of the door up to the top of the window frame. Pry out the two plastic pins on the leading edge of the door frame and work this trim piece loose. Take particular care near the door hinge - the trim is split behind the hinge so it can be removed, but it can be easily bent.
Continue working upward, loosening this trim. It will expand out to the grill of the HK tweeter and up into the window frame, where it contains the "anti-trapping" tape-switch (to prevent people from being caught in a closing window). You don't have to remove it completely (and it would be a pain to put it back on) - just release it enough to uncover the HK tweeter. You'll see a 2-pin white cable for the anti-trapping switch there. You should just be able to let this trim piece hang without needing to disconnect the cable.
At this point you need to get into the sound deadening foam glued to the door. This is fragile, gooey, and a general pain. The idea is to undo as little as possible. You'll see a bunch of wires coming out of the bottom of the HK tweeter. Two are for the tweeter; the rest are the mirror controls. These will duck under the sound deadening foam, loop around, and come back out at a lower level. They then run over the front of the foam to a control box near the front of the door, about 2/3 of the way down. That is the mirror control box. Once you have an idea of the scope of the work, carefully peel the foam back without ripping it to expose the mirror cable. The foam is held on with a sticky rubber compound (be careful not to get it on any other parts of the car). Once you have the foam peeled back, you should see the complete path of the mirror wiring harness. Undo the clip holding the mirror harness to the mirror control box and work the cable free. Parts of it will be covered with the rubber goop, and in two places there will be clamps holding it to the door frame. You can repeat the speaker clamp trick with this - your new mirrors come with new clamps pre-attached to the harness.
Now, look at the HK tweeter. You'll see it is held in by a screw at the top and slides onto another screw on the bottom. Remove the top screw and slide the tweeter off. You can just let it dangle - it isn't heavy enough to damage its cable. You will now see two more identical screws below the one you removed (they form a triangle). Support the mirror by reaching out through the open window and remove both screws. You can now work the mirror free. It will probably be stuck to the rubber window gasket, and there is a foam gasket below it. Work it free and gently feed the mirror wiring harness out the hold. Set the mirror aside and unpack your new mirror.
The new mirror also has a foam gasket dangling on the mirror harness. Feed the connector end of the new mirror's harness through the hole in the door and let the harness dangle inside. Position the new foam gasket inside the door frame cavity, taking care to align the holes in the gasket with the mounting holes in the door frame. This will take a couple attempts to get it right. Now, move the new mirror frame up to the door frame and get a feel for how it should attach. Once you have done a few test fittings and have a working plan, support the mirror with one hand while you look through the door frame holes from the inside. You should see the mirror mounting holes lining up with the door frame. Insert one of the 3 mirror mounting screws you removed and tighten loosely. The mirror mounting plate holes are not tapped, so you'll be cutting threads in the casting. When the mirror starts to snug down, stop and repeat with the other two screws. Take a look at the mirror from a number of angles to see how it sits on the rubber gasket at the top of the door as well as at the front of the door and the seam between the lower edge of the mirror bracket and the outside door trim. Wiggle it around to make it look like the other side. You may need to remove it and try again in extreme cases. Pay particular attention to the rubber weatherstripping above the mirror - it flares out near its lower end, but it is easy to bump this and misalign it. Once you have the mirror adjusted properly, tighten the screws all the way (you'll feel a definite increase in resistance once they're fully seated). Check the outside fit and finish one more time. If it is good, remove the top screw, re-attach the HK tweeter, and re-install the screw.
Now, work the mirror harness into the door foam using the same path as the old harness. Once you are sure you have the correct route, pop the clamps into the holes in the door frame and plug the connector into the control unit in the door frame.
At this point, you might want to temporarily install the new window switch on the driver's side and re-connect the battery to test out your new mirror. You can do this with only one side done. Make sure you have full function (normal tilt/pan, folding function, and reverse tilt if you're working on the passenger side).
You now have to make some repairs to the door foam to prevent rattles and leaks. You'll need 3M "Windo Weld" - the TIS calls for 1/4" which is impossible to find around here. I used the next size up (5/16"). This is the rubber goop that holds the foam to the frame. If your car has door/speaker rattles, you'll also want some silicone goop.
First, use the silicone goop (if needed) and put a dollop over the connectors that connect the HK tweeter and the window anti-trapping switch to the door harness (these are under the foam you'll be re-attaching next). Let dry. Take some short pieces of Windo Weld and put them on the door frame at the edges of the foam. Now press the foam down solidly to seat it.
While that is drying, look at your door liner. You'll see that the woofer is held in by 3 Philips screws and the midrange by a threaded collar. Make sure all screws are tight on the woofer and the collar is tight on the midrange. Tighten as necessary. Also, look at the back of the midrange. You'll see a clip that holds the connectors for this speaker. In my car, this is where the HK rattles come from. Save this thought for later.
Now, work the window anti-trapping switch / HK tweeter grill piece back into position. It needs to pop into place around the door frame near the HK tweeter. Make sure you have the anti-trapping switch seated properly as well - you don't want the window to roll up and go "crunch", or worse, "crack". Again, comparing with the other side is very useful. Once you're sure you have the anti-trapping and HK grill parts done, re-position it at the leading edge of the door, again taking care around the hinge area. The edge of this trim will slide under the foam weatherstripping in the middle of the leading edge of the door. Re-insert the two plastic pins (the holes should be well lined up between the trim and the door frame if the trim is properly aligned).
At this point you might want to make sure your window still operates properly. In any event, if you re-connected the battery you'll want to disconnect it again now - you'll be pounding on the door near the airbag shortly.
You are now ready to re-attach the door liner. Make sure everything else is done properly first - you don't want to go back in here if you don't have to. Plug in the woofer cable, then the midrange cable. Tap the speaker cable clamp back into the hole in the door liner that it came out of. Drop another blob of silicone on the back of the midrange, getting both halves of the connector, the bracket, and the back of the tweeter. Support the door panel on something (I used a 5 gallon bucket) to let the silicone set up for a bit.
Once the silicone is set, re-attach the door latch to the door liner and make sure the clip catches. Carefully align the door liner with the door locking pin. Now wiggle the door liner up and down and left and right until the rectangular clips at the top of the door frame line up, and tap the door back onto the clips. You now have to align the many round pins sticking out of the door liner with the matching holes in the door frame. I found it useful to lie on the garage floor, looking upward, with a flashlight and a dental pick to move the pins around as needed. When they are all aligned, pop the door liner back onto the door frame (I used the palm of my hand). Check for fit & finish all around - if there is a bulge between the edge of the liner and the door frame, you either have a misaligned pin or one that isn't popped back in. Repeat as neccessary.
Re-install the Torx screws (in the armrest and under the trim to the rear of the handle). Remember, the longest one goes near the door handle. Again, if you did this right these should all line up.
Re-install the window switch (driver's side) or filler (passenger's side), the two covers under the armrest, and the wood or plastic trim.
Re-install the painted mirror housing, again being careful of the 4 clips. Make sure the clips are completely engaged before the next step.
Re-install the mirror glass, being sure to re-connect the heater wires.
Repeat on the other side.
When you are done, you will need to re-set your mirror memory.