This instructiable details how to repair a Mini cooper door lock actuator. I did this to my 2003 mini cooper s. I was sick of reading about the countless number of people who have been forced to replace this poorly designed component with a new one ($130) because BMW made them "non-serviceable". This unit IS SERVICEABLE - if you are clever enough ;)
I would also like to thank the guys over @ NAM (northamericanmotoring.com).
Step 1: Are You Sure You Have a Broken Unit?
Confirm that in fact you do have a bad door lock actuator. Check  fuses  other door locks functionality  wiring harness  battery in your keyfob.
get your tools ready. I used torx, flat head screw drivers, pin, acetone, multimeter, DC-power supply.
Step 2: Remove Door Panel
Best to disconnect battery first.
Instead of "re-inventing the wheel" - check out this guys video: http://www.youtube.com/watch?v=wC0ciLIp6YY
Note that - the clips holding the panel on are pretty robust. there are three clips on the left side, right side and bottom that all pull srtaight out. The clips on the top also pull directly out from the door - not "up and out/' like they say in the video.
Step 3: Remove Lock Mechanism From Door.
there is al ot of info out on the web about doing this. Below is a quote from: http://new.minimania.com/web/SCatagory//DisplayType/Technical%20Information/DisplayID/2519/ArticleV.cfm
Note that I had to loosen the rear window guide. I also would highly reccomend removing the metal flange that holds the outside door lock handle cable. This will make removing the unit much easier.
Door Lock Repair Instructions, as submitted by 'MPayle' in our forums:
Instructions for replacing the door lock actuator on 2002 to 2006 MINIs.
These instructions are written from memory based on having replaced both the passenger and driver side actuators in a 2002 MINI Cooper-S over 7 years of ownership. Pictures are not available as I no longer own that particular car.
Replacing the door lock actuator is necessary when the lock stops properly responding to lock and unlock commands from the remote or dash mounted toggle switch. The same procedure is followed for either door; however the driver side actuator does take a bit more time to install as it has the key lock linkage to also get back in place. The passenger side takes about 1 hour to accomplish and the driver side takes about 1.5 hours. Leave the window rolled UP while doing all work - you need the room! You can get usually away with leaving the battery connected when changing the passenger side actuator;, however, you must disconnect the battery when changing the driver side actuator. The actuators act in a master-slave relationship with the driver side being the master. Disconnecting the battery will allow them to resynchronize when the battery is reconnected.
Tools necessary: #20 Torx driver #30 Torx driver small flat blade screw driver medium flat blade screw driver #2 Phillips head screw driver socket set (metric) flashlight
First, you must remove the door panel and carefully disconnect the speaker connections. The door panel is held in place by 4 torx screws (either #20 or #30) and a series of clips around the perimeter.
Three of the torx screws are in obvious locations: the recesses in the panel. The fourth is hidden behind the small clear/white reflector slightly below the lock button at the back of the door. Use the small blade screw driver to carefully pry up the reflector to remove it from the door and put it aside (where it won't get lost or damaged, so you can re-install it later). Remove all 4 torx screws - keeping track of which holes each one came out of: 3 are identical length, 1 is longer and has to go back into its original location.
Then use the medium flat blade screw driver to carefully pry up the perimeter of the door panel. I start at one of the lower corners and work along the bottom then up each side. The top is held in by spring clips that remain on the window edge of the door - be very careful getting these to pop free of the door panel. To release them, lift out very slightly on the bottom of the panel and then firmly pull the panel away from the frame. DO NOT PULL TOO HARD OR TOO FAR! You just want to pull it away enough to reach behind and disconnect the speaker wire connections: the lower speaker stays on the door panel and the upper speaker (tweeter) stays on the door frame though its cover stays on the door panel! Once the speaker connections are released, set the door panel aside.
The push rod for the manual lock will now be loose from the door panel. It has the black plastic tip on one end and the other inserts into a clip on the actuator. Reach into the door frame and find where the push rod goes through the grommet in the door frame and follow the push rod to the actuator. Pull the end of the push rod out of the actuator and feed it back through the grommet and set aside.
Next, you need to disconnect the electrical connector for the actuator. The connector is on the bottom inside corner of the actuator. It is held in place with spring clips on the sides of the connector. Simply squeeze the sides together and pull the connector down at the same time. Just let the connector drop to the bottom of the door until you need it for reconnecting.
You will easily be able to see the cable for the interior handle. The exterior handle is also a pull cable. Removing the interior handle assembly from the door frame and releasing the cable from the retaining clips will give more flexibility for getting the old actuator out and the new one in. The handle assembly is held in place by 3 phillips head screws (again, note where each screw comes out for re-installing).
You will also see the rear window guide about 1/3 the way from the back of the door. This is held in place by a bolt in the bottom of the door. Make note of exactly where (inside to outside) the bolt head is located before loosening it - DO NOT remove it - only loosen the bolt to allow in/out adjustment of the guide channel (again, to give more room to work inside the back of the door). Next comes loosening and removing the actuator.
Before loosening the 3 #30 torx screws that hold the actuator to the end of the door, use the flashlight to look inside the door and examine how the two cables are attached. You may need to re-use the clip that holds the exterior handle cable. You will nee to release the end of the exterior handle cable from its retaining clips before trying to remove the actuator. YOU WILL BE DOING THIS BY FEEL! While examining the connection with the flashlight, squeeze the outside handle to see the cable function. You will be able to then observe how to get sufficient slack in the cable to free the end from its retaining clip and then free from the white plastic sleeve guide. Be careful to not break the sleeve guide, it gets re-used. The sleeve guide rotates in its bracket and can fall out as you remove the actuator once the cable is free. The cable end is like a nail head and fits through a slot in the bottom tab on the actuator. You pull down on the cable and tilt the end of the cable to flip it out of the tab.
You will still have the interior handle cable attached to the actuator. Its attaching clip on the actuator is under a hinged cover. You will find it easier to remove this cable after you get the actuator loose and out of the door frame enough to open the cover, thus the freeing of the handle assembly and cable from the retaining clips along the door. Observe where the interior handle's cable is routed as you will need to ensure it gets routed the same way with the new actuator. You will be pulling the cable out around the window channel guide, so you will be sliding the interior handle close to the channel guide. Remove the three torx screws that hold the actuator to the door (should be #30). Then jiggle loose the actuator and work it out of the door far enough to open the cover and release the interior handle's cable. This will test your puzzle solving skills as you are in a tight space, working around the window guide channel with a relatively bulky 'L' shaped actuator. You have to snake and rotate it around the guide channel to get it out. Be careful to avoid putting a sharp bend in the handle cable. Pay some attention to how you get it out as inserting the replacement will be similar.
NOTE: if doing the driver side, there is also the control rod for the key lock. This is a rod with a u-joint style hinge near the key lock and a star head at the actuator end. The star fits into a socket in the top of the actuator and will be fairly clear to see when examining with the flashlight before removing the actuator. The star just slides into the fitting in the actuator. Getting the star back into the new actuator makes the driver side job take a bit longer than the passenger side.
Once you have the old actuator past the window guide channel and to the opening in the door frame, you can then open the retaining cover for the interior handle cable and free the cable from the actuator. Try to keep the cable from snapping back into the door Compare the old actuator with the replacement as there are a couple of small brackets you may need to transfer from the old actuator to the new actuator.
At this point one could use the classic phrase from the Haynes manuals: "assembly is the reverse of disassembly", but that would not be completely fair. Much of the re-assembly is the reverse of the above procedure, but there are steps that should be highlighted again anyway.
After transferring any brackets and/or clips necessary from the old actuator to the new actuator, make sure the interior handle cable is still making the "u-turn" around the guide channel and attach the cable to the actuator and secure the retaining cover. You may want to use a small piece of tape to help hold the white plastic clip for the exterior handle cable to its slide bracket. Manipulate the new actuator back into the door frame and past the guide channel. Pull some of the slack in the interior handle cable back outin order to help align the new actuator. As you manipulate the actuator into its position, you will need to ensure the exterior handle cable is not trapped behind the actuator as it needs to come over the top of the actuator to reach its guide clip and retaining clip.
NOTE: If doing the driver side door, you will also need to position the key lock rod into place for the star end to slide into its place in the actuator.
With the actuator in position, start threading one of the three torx screws that hold it to the door. This will hold it in place enough while you reconnect the exterior handle cable. This will again be mostly by feel. You will need to thread the cable into the guide clip then pull it down enough to tilt the end and slip it into the retaining bracket. Then thread the other two torx screws to hold the actuator to the door. Snug the screws down, but not fully tight - just enough to hold it still in place.
Remount the interior handle and its cable to the door frame. Thread the manual lock push rod back through the grommet and insert the end into its clip in the actuator. You should be ready to manually test the lock to be sure the cables are functioning. Use the manual push rod to lock and unlock the door. With the door unlocked, see if the outside handle cable is operating correctly. Use the push rod to lock the door. Pull the interior handle once to see if it unlocks the door. the second pull should then open the door.
If all this is working, fully secure the actuator to the door by tightening the torx screws to "hand tight" (about 14 lb-ft torque). Now reconnect the electrical plug for the actuator and then reconnect the battery. Fully test the actuator with the toggle switch on the dash and the remote control.
If satisfied that all is working, it is time to re-install the door panel. Do not forget to reconnect your speaker! Snap the door panel into place starting with the top, down each side and then along the bottom. Then replace the torx screws in the same locations they came out of. Put the reflector back over the fourth screw. You will also need to reprogram your radio presets and set the time on the clock.
Step 4: Repair Broken Actuator
Everyone out there say to "replace" the actuator for the sole reason that they are "not serviceable". This is BuII SH1T. These actuators do not work by magic - they fail for a reason. Most often it is a motor problem.
What we are going to have to do here is take apart the broken actuator. Start by removing the plastic cover that is clipped on. it will come off real easy.
Step 5: Dig In
with the cover off we need to start being every careful that we do not loose any springs etc. this thing is like a mechanical clock inside and can be very intimidating if you put anything back incorrectly.
Step 6: Take Note of How the Levers Are Positioned
I would highly suggest snapping a few photos - so that you can remember how the thing was put together. it does get very complicated very quickly.
Note where the metal levers are placed. Where they interlock and where they slide in.
Step 7: Remove White Plastic Lever
First remove this plastic lever
Step 8: Remove Gear
remove this black gear. Note there is a spring underneath. Make sure you note the orientation of the spring for the re-instillation later
i took a photo of the spring. The "s" part wraps around the plastic base and the "pin" part goes up into the gear. - I hope this is clear.
Step 9: Remove Torx Screws
I believe there are 4 torx screws. - Pull them out now
Step 10: Remove Compression PIN
there is a pin that must be removed. It is a straight pin in the center with a clip that must be removed off of it. I suggest digging a screw driver into the plastic under this pin and prying it off. I broke mine - but decided to still put it back on during re-assembly.
Step 11: Remove the Base Part of the L
the actuator can be separated into two parts the base part (white plastic ) can be separated from the metal part. it is held in by clips - observe where they are - apply a bit of pressure and fore apart.
Step 12: Clip Time
The whole unit is now being held together by clips and the plastic is very brittle. I suggest grabbing a plastic soda bottle and cutting a whole bunch of little shims. I take the little shims and slide them in between the clips that makes popping the unit open much easier. One of the things i was afraid of was there being a whole bunch of springs inside the unit that would pop out and be impossible to put back into place. Fortunately - this is not the case. - So fear not and open up the casing.
you can see the green soda bottle i cut up in the photos.
Step 13: Lets See Whats Wrong
Ok - It is time to diagnose what is wrong in here. The motor on the right is to open the lock. The motor on the left is to lock the lock. Visually inspect the two. On mine you can clearly see the motor on the right has a lot of "black stuff" around it.... I bet that is the trouble maker....
I removed both motors and hooked them up to a 12v power supply. Sure enough the motor on the left was bad... Not working at all.
Step 14: Take the Motor Apart
Although these motors are generally considered non-servicable - so is this entire actuator! So lets just open it up. There are two tabs on the side of the motor. Pry them apart and slide the back of the plastic housing off the motor. I dod this to reveal that my motor is filthy with black powder (most likely graphite worn off from the brushes).
you can see the little tabs that i bent out. They look like little nipples on the side of the motor.
Step 15: Clean Motor Contacts
It is important now to clean the contact s of the motor to make sure they are not shorting out during motor operation. I suggest reading the wiki page on how a motor works to understand why this is important. :)
I used a pin, some paper towels and nail polish remover. I dont suggest the nail polish remover - as it did not work that well - but it was all i had on hand . The contacts should be shinny copper color. (not shown in photo)
Step 16: Make New Plastic Washer/Bushing
When taking my motor apart I noticed that it had a plastic washer on the motor rod that was half burnt off. I am not sure if this was an insulating washer or a bushing - but i decided to make a new one to replace the old one. Here again I used a soda bottle. Cut a circle and drilled a hole to replace the old one
Step 17: Put Motor Back Together
When re-assembling the motor it is VERY important not to damage the brushes. The brushed (which are really little graphite cubes) are spring loaded to ride against the motor contacts that you just cleaned.
When i re-assembled my motor I created a tool to hold the brushes apart - by bending an old paperclip into a v shape. I then inserted the paper clip through the outside of the motor housing to hold the brushes. I suggest you do something similar because if you toast the brushes you have toasted the motor.
Step 18: Put Everything Back Together
Once the motor is re-assembled - test it with a 12v power source. I was able to get my motor to run down to about 7 volts - so they are a bit flexible. Note that depending on how well you cleaned the contacts on the motor you might have to give the motor a quick spin with your fingers to jump start it to moving the first few times. If you have to do this more then 5-6 times of on and off - then your contacts are not clean enough and you need to take the motor back apart. I had to do this once.
Well - thats about it. Put everything back together. Hopefully everything lines up. Test it on your car BEFORE you reinstall.
Hope you found this useful. IF you decide not to rebuild your actuator - throw it up on ebay - i am sure some one will appreciate being able to buy it ;)
Fredv26 made it!