Can E39 door lock actuators be repaired?

**Santaclaus4** · 07-22-2018, 01:18 AM

I just replaced both rear door lock actuators on my 2003 540i6. They appeared to be origonal so a 15 year life isn't all that bad. However, I didn't see anything wrong with them. They were clean and nothing appeared broken. I'm thinking I can disassemble them, clean and re grease them and use them as spares.

**JimLev** · 07-22-2018, 09:01 AM

Post some pics when you take them apart. Mine are 18 yrs old, never had any of them out.
Never have had to replace a window regulator either....knock on wood.

**Santaclaus4** · 07-22-2018, 09:15 AM

Will do...
They weren't broken, just getting really slow.

**JimLev** · 07-22-2018, 09:19 AM

Then a clean and lube could be all they need.

**pleiades** · 07-22-2018, 09:22 AM

Originally Posted by Santaclaus4

I just replaced both rear door lock actuators on my 2003 540i6. They appeared to be origonal so a 15 year life isn't all that bad. However, I didn't see anything wrong with them. They were clean and nothing appeared broken. I'm thinking I can disassemble them, clean and re grease them and use them as spares.

Prying off the outer casing is about the only slightly difficult step as you don't want to crack it. The sliding and rotating gear parts inside are entirely plastic (probably delrin). The only thing that you might be able to replace is the small motor, which resembled the type used in certain slot cars, but the two challenges with that are finding motors that have the same polarity (don't work in reverse of how the motors in these units work) and that come with the small pinion gear attached ... You might be able to pull the original pinion gear off the shaft but, if my memory isn't deceiving me, it's brass and may not fit or stay attached to another shaft solely with an interference fit.

I replaced my right rear door actuator not so long ago with a cheap aftermarket unit. So far, it is working at least as well as all the rest. The actuators in the BMW all make a buzzy zippy noise in operation. I can hardly hear the ones in my old Subaru.

I suspect the reason they fail is that the tolerances in the plastic gearing simply get too loose after more than a dozen years.

**M5XTu** · 07-22-2018, 04:21 PM

As cheap as the parts are, rebuilding them does not make economic sense.

Getting the parts and pieces to replace the worn out parts within (if available at all) will probably cost as much as a new one.

Sent from my iPhone using Tapatalk

**pleiades** · 07-22-2018, 08:54 PM

I agree. Lubing the old ones with a compatible lubricant to keep them around as spares is about the best you might hope for, but with functional aftermarket units going around $18, I don't think I'd even want to put an old one back in my car.

**Santaclaus4** · 07-22-2018, 09:14 PM

With a lifespan of 15 ish years, it's probably a waste of time and storage space to keep the old actuators around. It was more about the satisfaction of fixing them up and just plain old gee-whiz. Never the less, I'll take one apart and photograph it for forum and personal curiosity.

**Santaclaus4** · 07-30-2018, 10:42 AM

I finally took apart one of the old door actuators. I took pictures that I'll post a little later.
I can't find anything wrong with it at all. The gears moved smoothly and still had lube on them. The electric motor felt smooth.
The door locks must get slow due to worn or dirty contacts/brushes in the motors. I didn't disassemble the electric motor itself.

**Santaclaus4** · 08-03-2018, 05:02 AM

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**Santaclaus4** · 08-03-2018, 05:26 AM

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- - - Updated - - -

This is what the actuators look like. I disassembled it a little further but can't upload the picture at the moment. I have more photos but I can't upload them at the moment.

**atobe** · 08-04-2018, 06:52 PM

I have two of these that i replaced too. I can't find anything wrong with the mechanisms either. There was a thread where someone actually replaced the motor. My guess is that the brushes inside have worn out and not making good contacts anymore for the motor. His problem the motor was not getting good contact and he redid the solder and it worked. Mabuchi FC-280PC-22125 is the motor, but ours has spline shaft these motors are just plain shaft.

**JimLev** · 08-04-2018, 07:02 PM

Thanks for the pics.
How long do you think an $18 aftermarket actuated will last??

**dme88** · 08-05-2018, 03:52 AM

I've tried. Took one appart, lubricated and such. Worked for 2-3 weeks. Turned out all the plastic gears was very slightly worn, and the housing flexed - so had to buy a new one. Even the off brand cheap china cones is ok, if you don't mind their noise...

**HoZy** · 08-05-2018, 03:54 AM

I have a cheap ebay actuator in mine (Factory actuator lost a plastic tooth), it's locked/unlocked a couple hundred times so far. Apart from being slightly louder than what was from factory it works just great.

Best thing I ever did was clean and lubricate all the locking/latch mechanisms driver door opens with a finger and sometimes I doubt if I shut it because it pops open at the touch of the handle now.

Just need to do the other 3 doors... that's a job for future me

Cheers
Mat

**Santaclaus4** · 08-05-2018, 11:21 PM

I just tried to upload the remaining disassembly pictures but I get a message that says something like I've reached my forum limit. Something like that anyway.

**JimLev** · 08-06-2018, 09:25 AM

Originally Posted by Santaclaus4

I just tried to upload the remaining disassembly pictures but I get a message that says something like I've reached my forum limit. Something like that anyway.

Were you trying to upload more than 5 pics in your original post? 5 is the limit unless you do it in a different post.
Nate PM'ed me last week with the same message.

**Santaclaus4** · 08-06-2018, 06:12 PM

Originally Posted by JimLev

Were you trying to upload more than 5 pics in your original post? 5 is the limit unless you do it in a different post.
Nate PM'ed me last week with the same message.

I uploaded 5 pictures at the top of this thread, then I was able to upload 2 more. Now I can't upload anymore, even way down here.

**JimLev** · 08-06-2018, 06:55 PM

Try over on the TEST forum to see if you can post a few there just to see if it's a forum problem or a SC4 problem.

**Santaclaus4** · 08-06-2018, 10:06 PM

Originally Posted by JimLev

Try over on the TEST forum to see if you can post a few there just to see if it's a forum problem or a SC4 problem.

Just tried to upload on the test forum and got the same message: file size exceeds forum quota by (this many) KB.

**JimLev** · 08-06-2018, 10:29 PM

Don't know what your file size is? I usually resize the pics to around 960 X 800. The actual JPG file is around 350KB.
You using a PC or Apple?

**computiNATEor** · 08-07-2018, 04:20 AM

I can usually upload anything, including unedited, non-compressed iPhone photos and the website automatically downscales the images. However, when I tried uploading from my Canon t3i recently, I got a forum quota exceeded error. I did not attempt to resize them; I will try that next.

**balidawg** · 12-24-2019, 07:27 PM

Just to add to the actuator info here. I recently replaced the one in my right front door and disassembled the old one for kicks. Below is just my observations and notes for what it’s worth.

The actuator plug pin definitions, as deduced from the X1131 pinout.
https://www.newtis.info/tisv2/a/en/e39-530i-lim/ZZYmw2b
pin 1: ground to lock
pin 2: no connect
pin 3: 12V supply
pin 4: ground to unlock

actuator schematic
https://www.newtis.info/tisv2/a/en/e...r-door/uQr4rAu

- When directly powered on the bench, the defective actuator worked, but the motor ran slower than the fully installed actuators on the car. And this is running unconnected, with no load.
- Resistance across the electric motor was about 6.4 ohms.
- Lubricants on the screw shaft (yellowish grease) and gears (white grease) was still pliable and doing it’s job. Turning the large gear by hand revealed no binding in the gears, screw shaft, etc.
- The grey plastic lever that rides on the screw shaft which does the locking/unlocking had a lot of side-to-side play, causing it to not always activate the micro switch. This is likely what caused mine to ultimately fail.
- There is a discoloration on the plastic area between the motor’s electrical terminals and right under a passive component (capacitor?) connected across said terminals which suggests overheating at some point.
- The replacement actuator was an OE VDO brand which was not cheap.
- The original actuator had a revision code of 406.207/5/1 and date code of 2002.
- The OE replacement actuator had a revision code of 406.207/5/2 and date code of 06.03.2017.
- Although the screw shaft is about 2” long, the full travel for lock actuating is less than 0.5”.

**balidawg** · 12-24-2019, 08:06 PM

More photos...

**Santaclaus4** · 12-24-2019, 08:57 PM

I have noticed something vaguely interesting. On both of my cars, it's the rear door actuators that failed, the front passenger door actuator is a little slow but still works and the drivers door is still original on both cars and the locks snap up and down like normal and at the same speed as the new rear actuators. I wonder if it's related to the rear doors not opening and closing as much as the front doors. The drivers door is the one that gets both locked/unlocked every time and open/closed every time.
Maybe it's a coincidence but it seems like lack of use is a problem. I dunno...