Project E36 M3 - Replacing the Window Motor and Regulator October 04 2013

The officer didn't seem pleased as I tried to talk to him through the sunroof. "I don't mean to be rude, but my window doesn't roll down," I explained. "Can I open my door instead?" "NO," was his emphatic response. Apparently, he really didn't like open doors. He walked around to the passenger side of the car. Sensing the tension of the moment, I choose not to be a smart ass and lie about the passenger window not being able to roll down either. A few minutes later, I took my ticket through the fully functional passenger side window and continued on my merry way.

The defunct window motor on our E36 M3 was making it difficult to speak with the friendly local law enforcement officers, and paying tolls with coins was awkward. It was time to replace the window motor. A lot of people go ahead and replace the window regulator at the same time, since it is easy to mess it up when drilling out the rivets.

So let's get to it. We'll take off the door panel to access the window motor and window regulator. Before we start, it is important to disconnect the battery and wait 20 minutes to reduce the risk of setting off the airbag in the door. There are capacitors that keep the airbags active for a while after losing power. One might shrug at the risk of a puffy bag inflating in one's face. If you have ever seen an airbag prank on the internet, you will know that these devices pack a lot of violence in them.

So let's get started. We start by removing all the trim pieces from the door.

Remove these two covers by the pull handle. I used a nylon pry bar. The nylon is less prone to scratching than a screwdriver.

The airbag badge actually hides a mounting screw behind it. This badge needs to come off.

Remove the frame of the door handle by pushing forward on it. Make sure you're pushing on only the frame, since the recessed portion does not come out. I used the handle of a screwdriver to push on it.

This is what the frame looks like. You can see the hooks that hold it it.

Next was the window switch. Once the switch is out, remove the switch from the connector.

Now with all the covers and trim pieces off, we can undo the three screws that hold the door panel on. Two are by the pull handle, and one is behind the airbag badge. The screws are Torx screws, so you'll need a torx bit.

Now, the door is only held on by some snap-in, plastic fasteners. I put a pry bar next to the fasteners and pried outwards.

Here is a photo of the door and the locations of the plastic fasteners (white).

Once the panel is free, disconnect the wires to the speakers and place the panel off to the side.

Next is the scary part: removing the side airbag. I stay as far away as I can while disconnecting the harness and never put any tools in between me and the airbag. In retrospect, I should have put on my racing helmet while doing this. Once the airbag is disconnected, undo the four bolts holding it in and place the airbag somewhere safe and far away. Don't store it face down, because if it goes off, it will likely fly upwards through your ceiling.

Next, remove the foam vapor barrier. It is held on by a tar-like substance. Peel slowly and carefully around the edges until the whole piece is free. If you end up getting that tar somewhere undesirable, Goo Gone removes it efficiently. Once removed, place the vapor barrier somewhere safe. I left the tar in place and when it came time to reinstall the vapor barrier, it pressed into place with no problems.

Now we have access to the window motor and regulator.

Mark the position of the adjustment arm with tape or a marker. This will help tremendously when putting everything back together. Now that you've marked the position, you can remove the bolt that is holding the adjustment arm.

In order to replace the motor, the regulator has to be removed to access the screws that mount the motor. The regulator is held on with four rivets that need to be drilled out. Carefully drill off the head of the rivet and then punch the rivet out with a center punch. If you drill too far, you'll end up making the holes in the regulator too big and you'll need a new regulator. I had planned on replacing the regulator anyways. If you drill ever farther, then you end up making the hole in the door larger, and then you'll have to come up with a clever way to fix your problem - probably by installing a larger diameter bolt. Note in the photo how I had to move the wiring out of the way. For re-installation, I used stainless steel M6 bolts with washers and nuts to replace the rivets.

To remove the regulator, the window needs to be rolled down almost all the way, but since our motor was inoperative, we had to disassemble the motor to allow it to turn. Disconnect the harnesses to the motor and remove the four screws that hold the motor on. Once the screws are off, it will require a bit of tugging to remove.

With the window motor removed, the regulator can move. I put a towel between the regulator and the door to protect the finish on the door. Move the window down until there is only about 5 inches of window sticking out the top of the door. This will give us access to the regulator mounting points.

Undo the slide stop at the aft end of the rear slide. It is held on with two bolts seen in the center of the photo. When reinstalling these, make sure you don't tighten more than finger tight, or you will crack your window. Once the two bolts are off, slide the slide stop aft and remove it.

The regulator mounts to plastic sliders inside the slides. Undo the metal clips, and the regulator should be free. I used a hybrid method where I slid the aft connection point off the aft end of the slide, while I undid the metal clip on the plastic slider on the forward rail.

With the regulator removed, you can see the plastic slider (white) in the slide better.

Now install the new motor on the new window regulator. Transfer the wiring harness clips and the speed nuts from the old regulator to the new regulator. 

Prior to installation of the new parts, lube everything up with some white lithium grease.

Some of the plastic pieces (black) had come detached from the door panel.

I sanded the areas where the epoxy would go and then epoxied the plastic back onto the panel. You should be able to put everything back together now that you know how it all comes apart. Here are a few tips:

1) You will have to move the window back up to be able to install the mounting bolts (formerly rivets) that hold the regulator on. Make sure that any time the car is on, the airbag is plugged in. If it is not, it will throw an airbag code, and you'll need to get it reset at the dealership if you don't have the reset tool.

2) Be sure to check the door for any foreign objects before putting the vapor barrier back up. You don't want anything you left in there rattling around.

3) The new window motor has to learn the limits of its travel. Once the regulator and window motor are installed, press the switch to roll the window down and after the window reaches the bottom, keep holding the the switch down for 6 seconds. This will teach the window motor the limits of its travel.

I had heard from the interwebs that this is a difficult job, but once I got into it, it was easier than I had imagined. Now it's your turn to fix your broken window motor. Think of all the drive thrus you can go to, all the toll booths you can throw coins at and all the conversations with the law enforcement officers you can have through your window.

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