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      01-21-2022, 02:46 AM   #1
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Drives: E90 335i
Join Date: Apr 2018
Location: Sitting in a BMW.

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E90 BMW Soft close doors retrofit DIY-E9X Chassis.

Here's a proper DIY on adding the soft close doors to your E9X car.
No coding required!
Here’s a video of it working.

This DIY works for a lot of E chassis vehicles and other chassis, as long as the car uses the door actuator design/style that is used here.
My E70 has it and its super nice!
In this DIY, I'm only doing the driver door. Installation instructions may differ on the other doors, I will edit the post when I do the other doors...

The specific actuator I used does have a pinch hazard safety mechanism. If it senses pressure when pulling the the door closed, it will stop and return to the partially closed position. That doesn't mean you can leave your finger there, it still closes for a split second before opening back up. I put a pencil on the edge of the door when it was closing, it did open back up when it sensed the pencil but in that split second where it closed, it crushed the pencil!

Images are viewed best on mobile.

Soft close motor may be referred to as “SC motor”.

  • 1 Door Actuator w/ soft close motor from F10/F01 P/N 5121-7-185-789

  • 1 Self locking (or regular) nut to mount the SC motor.
    P/N 6450-9-123-157
The way I mounted the motor, I only used one nut. There are 3 mounting studs on the SC motor. You will need 3 nuts if you're making a custom bracket, I didn't need to make a custom bracket. These nuts are similar to the nuts that hold the speakers to the door panels or tail lights to the body, I had some extra ones.

  • 1 Soft close Motor electrical connector. P/N 6113-8-364-520
This is the connector that plugs into the SC motor.

  • 1 pair of connector pins P/N 6113-0-070-586
These pins slide into the black connector listed right above this.

Your door harness on the E9X chassis WILL NOT have this pigtail wrapped in the loom. I have seen this pigtail wrapped in door wire harnesses on E70 models that didn't have the SC motor, that's where I got my connector from, an old E70 door harness.

  • Black electrical tape

  • 2 electrical connectors
Using these, doesn't require any wire cutting.

Time to start! With no issues, this should take 1-1.5 hours.

First thing that's needed is to remove the old door actuator. I won't be showing this, but here's a link showing it, once you get to the point where the actuator is removed, come back here.

^They didn't remove the window regulator, which I highly suggest. Heres another link showing the regulator removal.

Now we can really begin

Step 1.) Photo #1 & #2
Your old actuator is attached to your door handle bracket with a cable. You need to remove the cable/handle bracket from the old actuator and attach it to the new actuator. It's straight forward, unclip the cable and clip it back on the new piece.

Now you should have 3 parts tied together:
Door handle bracket
Door actuator
Soft close motor
There is a yellow cover/cap on the back of your old door actuator, pop it off and clip it on the new actuator.

Step 2.) Photo #3 & #4-#5
Configure your black connector and electrical pins.
Since I used a piece from a used harness, I'll try to walk you through this step.
Based on the photos on the ECS site, it looks like its 1 single wire with 2 pins.
Cut the wire in half and insert 1 pin into each slot on the back of the black connector. You can label one as red and another as brown, or keep track of which is which. Once the pins are in the connector, give them a slight tug to make sure they don't come out and make sure they're fully seated.
The last thing you want is to have those pins/wires pop out when you put everything back together.
The connector I used had roughly 1ft of wire on it. This was barely long enough. If the ECS wire (when cut in half) is 1ft or less, I recommend extending it a little. Once the motor is mounted, its hard to work with the wires.
The top pin on the black connector will be your positive/power wire. See photo #3, take note of this wire so you can wire this one to the power on the door harness later.

If you do not have an oem connector, in theory you should be able to use 2 female wire connectors to connect wires into the motor. See Photo #4-#5.
If you use this method, secure the wires to the motor so they don't come out! Also, note which pin will be the -/+. The orientation of the motor in photo #5 shows that the top pin (green wire) would be your positive cable.

Step 3.) Time to start re-installing NO photos
Start by pushing the parts back up into the door.
First goes the door handle bracket, followed by actuator and SC motor. Bolt the door handle bracket in place so it holds the rest up.
Now bolt the actuator in place and plug it in.
Make sure your SC motor cable is free and that the new wires you added are also free.
Put your door handle back on now.

Step 4.) Mounting the Soft close motor to the door. Photo #6.5 & #7
This step is a bit hard to explain. LOOK closely at my photos to see how its mounted.
At this point, your regulator should already be bolted in and wire connectors on the motor in place.
The cable length on the SC motor is just long enough to pop out of the door so you can mount it, that's why its important to have sufficient cable slack.

Only 1 stud on the SC motor makes contact with the door frame, so I bolted that one. I held the motor in place where the stud made contact, I then put my finger over the stud and pulled the motor away and left my finger on the door. I made a pinching motion with my thumb and finger (thumb was on the outside of the door) and where my thumb was touching the door, that's where I drilled a hole. See photo #6.5.
If you put the motor in at an angle, the bottom of the edge will catch the door frame on the outside while the top is bolted on from the inside. This tension keeps the motor in place. See photo #6.5

Photo #7 shows the motor in place and shows where I ran the motor wiring.(blue line). You can also see a hole I drilled earlier to mount the motor. That position did not work because it got in the way of the window track.


This method works great and the motor stays put. You're welcome to design some sort of bracket if you'd like!

Step 5.) Window track/regulator install.NO photos
Put your window regulator back on and make sure it fits without any issues. The studs on the window tracks should slide into their designated holes freely and evenly. You will mostly be paying attention to the rear track, if the studs don't slide evenly (top to bottom) then something is wrong and you need to re check the position of the SC motor.
Don't put the window back on yet until youre done with everything.

Step 6.) Locate Wires to pull power/ground. Photo #8 & #9
You can either run wires all the way to the fuse box or do the following.

Locate your window switch connector/harness. There will be 2 wires which we will pull power/ground from. Photo #8.
We will be using a RED wire with gray stripe and a brown wire from this connector.
DO NOT confuse the RED with gray stripe wire from the gray with red stripe wire.
Photo #8 shows the wires we are using circled.
The Red with gray stripe wire is a little thicker anyways, so you shouldn't get confused on which to use.
The brown ground wire is simple, just 1 brown wire on this plug.
NOTE! There is an additional brown wire in the same wire loom, this wire is used for the floor lights when the door is opened, DO NOT tap into this wire. I removed the factory tape to check which of the 2 brown wires went into the window switch so I could tap into the correct one.
Photo #9 shows this. Green=yes, Red=no.

Step 7.)Tapping into the harness Photo #10 & #11.
The clips I used have a metal plate that when squeezed down over 2 wires, makes small cuts on the wires and they make contact via the plate.
Slide the clip over a wire on your oem harness and slide the corresponding wire (red to red-brown to brown) from your SC motor into the clip. Squeeze the metal plate down with pliers and fold the plastic cover over it. See photo #10.

Tape it all up now. Photo #11 shows the harness taped, where the SC motor harness is ran, and a zip tie holding the wire up on an oem hole.

Now get out, tap your door closed and look at it work!

Once you've tried it a few times, verified its working and showed your family the modern technology door, time to put the rest back together. Really just slide the window back in place and put the vapor barrier and door panel back on.
Its a good idea, to test your window movement up and down before putting the door panel on to verify its not binding or getting caught on anything.

The placement of the motor makes for a very snug fit between the motor and door panel. The door panel clips and screws hold the panel in place just fine.

I will be updating this thread in the future for the other doors with SC mounting locations and wiring for them.

Attached Images
E90 335i 408WHP. Alpine over Terra brown
E70 X5 35i M Sport. Alpine over Black
E91 328 M Sport x2. Alpine over Black/. Sapphire over Saddle brown
E93 N54 DINAN tuned. Alpine over Saddle brown

Last edited by Serf27; 01-22-2022 at 01:29 AM..
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