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DIY: Do It Yourself
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Old 02-19-2016, 09:16 PM   #1
Registered User
Join Date: Feb 2016
Location: Arkansas, USA
Posts: 43
My Ride: 2004 325Ci
DIY E46 Door lock actuator/ Door ajar repair

My first DIY how-to, so hopefully it makes sense to everyone.

To start off, this write up is assuming you have the assembly removed from the door already. There are several how-to's on that so take your pic.
The first section is devoted to rebuilding the locking mechanism. If you are having problems with random Door ajar, or dome light turning itself on or off scroll down to the large bold text below the 1st section.
On this vehicle the door ajar switch was randomly turning on interior lights, and the lock mechanism itself was not functioning due to corroded contacts on the motors inside.
Estimated repair time: 3 hours including removal and installation.
Savings of DIY repair: $180-300 (USD)

Remove door lock rod from it's clip.

Grind the head off of the factory rivets. You may need to pry them up using a flat head screw driver afterward.

Remove the cable bracket leaving the exterior door handle arm. Pull up gently to remove the arm. You will feel the tension spring release as it separates.

Remove the center cap from the door lock rod arm.

Pry up the arm evenly with a flat screw driver until it releases. it will be tight!

Release the two tabs on the outer cover and remove.

Remove the serrated clip from the center pin and tap out.

Release the white plastic arm connecting the lower actuator arm.

Remove the actuator gearbox, by prying the plastic housing away from the steel plate enough to release the two plastic dowels and slide the unit apart.

You should be looking at the gearbox itself at this point. Note the arm positions. In this image both arms are located in the unlock position.

Release the tension spring on the white drive piece, and twist counter-clockwise to remove. You will probably have to pry up slightly for it to clear the stop on the gearbox housing.

Pry up the actuator arms using a flat head screw driver. Pry evenly so not to break them. They will also be tight.

Remove the 5 T20 screws and separate the housing., Try not to break the clips on the outer edges.

Inspect the gears for stripped teeth and remove from the housing.

Now you can remove the motors from the housing. They are clipped into place and easily removed with a thin pry tool.

Inspect the pin connections on the motors and look for black dust from motor wear and signs of arcing on the contacts.

Also inspect the pin connections coming from the board in the housing for corrosion or signs of arcing.

After cleaning the pins and reinstalling the motors I placed the lower half of the housing back on the main unit and tested the motor function in the vehicle to be sure both motors work appropriately.

The lower actuator motor should only turn on the unlock cycle. Whereas the upper actuator motor should turn on both lock and unlock.
If either motor fails at this step remove the motors and check voltage at the pins to ensure the board is good.
If the board is good, you can swap motors and check to see if this resolves the issue.

Replace the gear sets, minding the orientation of the gears for which cycle you need upon re installation.

Reassemble the gearbox and slide it back into the main unit. Be sure to check all arm positions as you reassemble to ensure correct operation.
The pin on the under side of the upper arm can be tricky to get into position as you assemble the unit so keep a watchful eye on it so as not to shear it off.

Replace the center pin and serrated washer with a 5mm screw and serrated nut for ease of installation or removal in the future.

Reinstall the exterior latch arm if removed and place tension spring back in correct orientation.

Double and triple check the function of the door latch before assembly. Ensure the plastic arm with the bronze magnets moves freely and does not hang on the edge of the steel frame.

Replace the plastic cover if desired. Place the outer exterior latch arm on it's pin and work the tension spring from the back side of the assembly to seat the arm fully.

Replace the cable bracket onto the steel rivets.
If there is enough rivet left they can be mushroomed with a punch to hold the brake. I prefer to do a small spot weld on the end of each rivet to ensure nothing works free over time.

Plug the actuator into the car and test the functions a final time before the installation.
After installation check the dome light and window drop functions work correctly.

Door ajar problems

The plastic arm with the bronze colored magnet operates the door ajar switch.

This magnet is very weak respectively and will degrade over time. It is originally just enough to function the magnetic switch made into the gearbox lower housing.
After they get weak the switch will sometimes intermittently show door ajar and turn on interior lights, or drop your window down for door clearance.
That solution comes in two forms below.

First, to check the function of the magnetic switch itself you can plug the actuator into the door.
Turn your key to position 2 and observe the door ajar display.
Manually activate the small magnet on the gearbox housing with a magnetized screw driver or similar tool and watch for the door ajar warning to change.
If the ajar display does not change, the switch itself my be damaged and is not repairable.

Solutions for a weak magnet.
1st you could try to re-energize the magnet. If you ever took basic science in school you probably learned how to magnetize things using a strand of wire. If not, it's simple enough.
Wrap a small gauge wire as many times as possible around the object you wish to magnetize and touch one end of the wire to the positive terminal of a battery. Then touch the other end of the wire to the negative terminal for a split second.
The problem with the magnet in this lever is the surface area is not large enough to wrap very many coils on, therefore it is difficult to re-energize. There is also a slight risk that you could reverse the polarity of the magnet and it would not function the switch.

The 2nd and more user friendly option is to remove the original magnet and epoxy a different magnet of appropriate strength on the outside of the lever.
I have used the 6mm magnets from telescoping magnets and they work flawlessly.

As always test the function of the switch before doing any irreversible work, such as epoxying a magnet to it.

This is a DIY for your own education. I accept no responsibility for damage to your vehicle or mechanism if you attempt this repair. If you are not capable of completing the tasks above, please do not attempt to repair this part. It is much easier to break than to fix.
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Old 02-19-2016, 09:17 PM   #2
Registered User
Join Date: Feb 2016
Location: Arkansas, USA
Posts: 43
My Ride: 2004 325Ci
The images are a little large, hopefully your browsers will auto size them accordingly.
If you have any questions about this process ask away, I'm here to help.
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Old 03-12-2016, 02:28 PM   #3
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Join Date: Mar 2012
Location: FingerLakes
Posts: 264
My Ride: '01 325 vert
This is awesome! I was wondering if anyone had found a way to fix these, and even searched for info, but nothing came up. idk if I have the patience to fix mine, but definitely appreciate the DIY.

Also I noticed a small, but very very helpful change in the later model actuator I replaced mine with. They flipped the clips where the external door handle connects. So maybe while it is apart we can modify it like bmw did.

Last edited by TynPar; 03-12-2016 at 02:31 PM.
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Old 03-12-2016, 02:46 PM   #4
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Join Date: Feb 2016
Location: Arkansas, USA
Posts: 43
My Ride: 2004 325Ci
Glad to see somebody took interest in this.
I thought it would be a nice addition to diy section.
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door ajar, door latch, lock actuator

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