I have the comfort seats with the extendable thigh support. This weekend I noticed that the support are not responding to the switch and can be easily moved in and out. I need to check once again to see if I can hear the motor running when the buttons are depressed, but I don't recall hearing it yesterday. Any ideas if there is a connection or something I might want to be looking at when I unbolt the seat to have a look?

I had the same problem on my passenger side. I had to go back to the dealer and had them replaced the motor. It was under warranty.

I have a 2006 530xi with comfort seats. My drivers side has had the same problem for a year. I decided to fix is a couple weeks ago. With the car off, you could hear the motor turning when operating the switch. The thigh support did not move at all and I could pull it out or push it back in. I replaced it myself. When I got the old piece out, there was a gear inside the reduction gear housing attached to the motor that was broken in half.

Unfortunately, I could just replace the gear. I needed part #2 in this diagram (52 10 7 068 045):
http://bmwfans.info/parts/catalog/E6...ations_electr/

Local dealer had that part -- $207 minus a 15% (CCA discount).

I think the repair manual would tell you to take the seat out. I didn't want to mess with that as it just involves some many other things. It isn't a hard job mechanically speaking, but if you don't take the seat out, you have very little room to maneuver and the assembly has to be partially disassembled in order to get it out. To get in back in, you have to partially disassemble it, put it back in, and reassemble a couple pieces only after it is back under the seat. Once I figured that sequence out, it went quick. Let me know if you need details on the procedure.

Thanks I spoke with no quarter today and he thought the same. I did confirm that the motor is working when the switch is moved and the sound seems normal, it just doesn't move. If you have some good info on how to get this out it would be much appreciated!

+1 thanks for the input in advance!

Here is a DIY to change out the comfort seat thigh motor and bracket. I got tired of mine not working a few weeks ago and decided to take it out and figure out what was wrong. In the end, an internal gear was broken. BMW does not sell the gear individually and I purchased an entire new motor and assembly. I didn't want to take the seat out, since I feared that was just more of a snowball than I wanted to deal with.

My symptoms were I could hear the motor when I worked the switch, but nothing happened. I could also freely pull the thigh support out and push it back in with my hands.

As with all DIY, your skill level is important. If you aren't comfortable with taking off trim pieces (they can break) or working with your fingers under the seat with limited mobility, you might want to not attempt this DIY. I'm pretty comfortable with these things. I'd say the whole thing took me a couple hours to get out and get back in. It would have been faster if I had figured out the need to disassemble the whole assembly first under the seat.

(1) Pry forward about a 1/8 inch the side trim panel. It locks the front trim panel on the side. Pry it by the arrow carefully. It only needs to unlock from the front panel just an 1/8 inch -- you don't need to remove the side panel.
Attachment 136464

(2) Remove the thigh support from it's brackets. Since it is broken, just pull the thigh support out with your hands. Look under the thigh support and there are a couple of torx bolts. Just take them out. Here is the bracket the thigh support is attached to (this picture is it off the car):
Attachment 136465

(3) Remove the two trim pieces on the front of the seat. These can be seen here:
Attachment 136466

The bottom one comes off pretty easily. The top one has some metal spring clips holding it pretty tightly. As I recall, it was pretty firmly attached, but the clips are metal and springy and not prone to breaking.

(4) Remove the plastic piece under the thing support. It gets exposed when you extend the thigh support. The picture I took was after it was all back to together. With the thigh support off, pull up where the arrows are (imagine the thigh support is off in my picture). Then slide forward. There are metal spring clips on the front of the plastic piece (front of the seat) and plastic tabs are the rear. DO NOT pry up on the rear or you could break the plastic tabs. Pry up on the front and remove it by pulling it up and sliding it forward.
Attachment 136467

(5) Once that is removed, you see a number of torx screws. These hold the assembly in place. I didn't disassemble mine again to take the pictures. This is a picture of the assembly as it comes from the package.
Attachment 136468

(6) Now comes the disassembly part. You cannot get the entire assembly out from or back under the seat as it looks in the picture above. What you need to do is disassemble the brackets from the bracket gear teeth. It sounds complicated, but it isn't really. Here is what each bracket looks like:
Attachment 136469

(7) Notice the parts marked by the ovals. These are accessible from above the metal that is under the part removed in step 4. What you need to do is unlock the tabs of this part for each of the rails. Here is what the top cover looks like -- this view is upside down and taken out from under the seat:
Attachment 136470

(8) This has tabs that lock into the piece seen in (7) -- this view is with the top piece removed and taken out from under the seat:
Attachment 136471

(9) So, the idea is, while the assembly is still under the seat, you unlock the tabs from (7) and (8). You need to do this on both sides. On the side farthest from the motor, you need to remove the underside bracket from the rod. It looks like this now (but, still under the car):
Attachment 136472

(10) Now you need to carefully unhook the motor connector. Use a small screwdriver to push on the connector latch. You can clearly see it on one side of the connector. Don't just try to pull the connector out without depressing the latch.

(11) Now you can get the part seen in (9) out from under the seat. You will need to wiggle and force it out when it seems like it is almost there. It does not just easily come out.

(12) Reassembly is the reverse. On the new part, unhook the rail brackets to make the new part look like (9).

(13) Get it back under the seat as shown in (9). It will not just easily slide under the seat. As I recall, I got it into a position that felt like was almost there and I pushed it a little hard and it popped over the metal tube under the seat.

(14) One side at a time, insert the loose rail as seen in (2) through the front of the seat.

(15) Insert the top piece seen in (7) under the seat and on top of the rail. Snap it together with the bottom piece. You will have to do some jiggling around to make sure the teeth align properly with the rail. Do the same for the other side. MAKE SURE the rails are sticking out the same on both sides when you snap the final side together.

(16) Now you can fasten the assembly to the top metal part of the seat.

(17) Hook up the electrical connector.

(18) Test it.

(19) Put the plastic piece that goes on top of the seat back.

(20) Reattach the thigh support.

(21) Reattach the two front trim pieces and lock the side trim piece back.

@twh

Wow, awesome write up. :notworthy: Thank you for taking the time to snap these pics and write up this DIY. My thigh supports are currently working fine, but I'm sure your post will help many members, and possibly myself in the future. :thumbsup:

Thanks!

Thank you so much for the write up.
Well it looks like I would never stand a chance to DIY this on my car... My skill level is too green to handle this... :wacko:

Thanks so much for the DIY and pics. Going to try that on mine.
In fact, driving a few days with it broken (bolster freely moving) made me realize there's likely a design flaw with this module. I extended it manually and drove like that for a bit, both of my legs extended. Then, I folded back my left leg and the foot hit the bolster with force, jolting it back into place (since nothing is holding it in place).
If it would have been operational, the gears would suffer the brunt of the force and seeing how small they are in the pics, I can't believe they can sustain such bumping for too long. I'm surprised they lastet the years the did.
I think this should have been a screw-type rack-n-pinion, not the gear-type that it is...

Just fyi...if your car is under warranty (either new-car or CPO) this repair is covered. Both sides on mine did the same thing and they were covered.

Excellent DIY post!!