Repair a Broken Power Window on a Car

In this entry, I show you how to fix a car's power window that won't go up or down anymore. The glass is fine. What's wrong is something in the power window motor, or (most likely) the regulator, or the horizontal arm.

Difficulty rating: 3

On a scale of 0-10, in which making rice in a rice cooker is 0 and using a sewing machine is 10, this project is a 3, as difficult as making tiramisu.

Time to repair: 3 hours if you have no experience fixing things, and need to futz around a bit. 1 hour if you've done this once before.

Ideal number of workers: 2

Tools & part needed:

• A shop light, or a flashlight
• A flat screw driver (for prying off door panel)
• A ratchet handle
• A 6-inch socket extension
• A T-20 Torx head socket (for the 5 door screws)*
• Tape (for recording proper location of removed screws)
• Note paper (for recording proper location of removed screws)
• Pen (for recording proper location of removed screws)
• A gallon baggie (for holding identified screws)
• A little clamp (for holding the door vapor barrier out the way. You can substitute a piece of tape)
• An 8 mm hex head socket (for the 3 assembly screws and the 1 window screw)*
• A replacement motor & regulator (with arm)
• Protective face mask (to protect against inhaling lithium grease)
• Lithium grease
• Electrical tape (for taping wires against door)
• Double sided tape (for putting screws back in door panel)

*These size sockets (and the number of screws involved) are for the screws on a rear side 2001 BMW 325i door and window. You should have whole socket sets to select the right sockets to accommodate the screws on other models, makes, and years.

The one part costs about $100 on-line. If you don't have the tools, you know someone who does, and you can borrow them. Otherwise, the tools will cost you <$100 and they are readily available at any decently-stocked hardware store.

Savings, compared to having a professional do this repair (assuming you can get together the tools without buying new ones):

$300-$800, depending on your model of car. $300 for a Toyota. $800 for a BMW.

Why do this repair yourself:

This repair is so incredibly cheap and easy and quick, and mechanics charge so very, very much for parts and labor on this one (all repairs on a BMW are priced assuming you have a US$1 million/year income, for example). Getting the window mechanism repaired professionally is just donating large amounts of money that you obviously don't have, because if for example the plastic window regulator parts are worn down, your car is about 10 years old, and therefore in all probability your household is making under $100K/year. Leave to the mechanic the repair jobs that actually require a mechanic--this one doesn't; there will be plenty of work and income for your mechanic if your car's old enough, or if she can tap into that top 1% income/wealth market.

Further, if one power window goes, the others are also slated for planned obsolescence; make these repairs more affordable by learning to do them yourself from the start. In encouraging you to repair your window, I also commend you for reusing, repurposing and reinvigorating your old stuff or rich people's castoffs in this, the era of astronomical social inequality and environmental crisis.

Ready, set, go

The minute your window stops rolling up or down, order up the replacement window motor & regulator from an on-line car parts retailer. Don't even go to the mechanic's shop. Just to have a mechanic look at the window, not even fix it, will cost as much (around $100) and take as much time out of your life (less than 3 hours) as just putting in the new part yourself on a Saturday morning.

Next, cut and paste and print out the How-to direction below.

How to:

1) Order a combined window motor and regulator for whichever window you need to replace (eg. rear passenger) from an on-line car parts store. This will cost around $100, including shipping, and the part will get to you within a couple days. I can recommend All OEM Parts for imports.

2) Remove the door panel. This is super easy. It will take you 15 minutes per door, if you've never done this before.

Photo 2-1

Use the flathead screwdriver to gently pry up the strips of plastic to reveal underlying screws. On our BMW there were two Torx screws along this strip.

Photo 2-2

Here is a ratchet handle with a T-20 Torx head socket on it. The torx screws are star-shaped.

Photo 2-3

See the round hole below and to the left of the lock? Use the T-20 Torx to remove this first (long) screw.

Photo 2-4

Tape the screw to a piece of paper and write a note reminding yourself where it goes. Put it in the plastic baggie. Repeat this procedure with all the screws (There are 5 Torx screws in total on a BMW door panel).

Pause for a moment to reflect on all the goodness that O-C behavior brings to our world.

Photo 2-5

There's a second (shorter) screw to remove near the door handle.

Photo 2-6

Use the flathead screwdriver to gently pry out the window up/down control. The wires for the up/down control are attached with a snap-on; pull the wire snap-on out.

Photo 2-7

Photo 2-8

Under the window up/down control there's a third screw to remove.

Photo 2-9

Photo 2-10

Under the door armrest are two screws behind plastic covers. Gently pry off the plastic overs with the flathead screwdriver. Then unscrew the fourth and fifth Torx screws. That's it for the car door panel screws on a BMW.

Photo 2-11

Now you can pull off the door panel. There will be a speaker wire bundle, the window power switch wires, and a door handle cable bundle attached. They will have easy snap-off connectors.

Photo 2-12

See? Such snap connectors are attached to the speaker. Easily snap them off.

Photo 2-13

Closer view of the speaker wires to be removed while you're repairing the window.

Photo 2-14

Pull the window power switch wires through the hole in the door panel. This will be obvious.

Photo 2-15

Easily pull off the door handle cable by pulling the white plastic end out of the black plastic door handle casing.

Pry off the door panel.

Photo 2-16

The vapor barrier (the dark material covering the door) is stuck on with black gunk. The handy part of the black gunk is that you can easily pull the vapor barrier off it, and reattach the vapor barrier to the gunk when you're done. Try to keep the vapor barrier intact.

Photo 2-17

Clamp or tape up the vapor barrier to the side. In the lower window of the exposed metal door we now see the automatic window motor, regulator and arm. We are ready to swap out the old motor-regulator assembly.

3) Replacing the automatic window-motor-arm assembly (This should take about 1/2 an hour tops, or up to 2 hours if this is your first time and you are investigating around.):

Photo 3-1

Here's what the automatic window motor-regulator-arm assembly will look like when it comes from the on-line car parts retailer. The black part is the regulator. The metal part on top of the black part is the motor. The regulator arm is the horizontal metal part. (As I recall, the regulator pushes the window pane up and down, as it travels up and down the vertical metal rail in the door. The arm holds the motor-regulator to the door.)

The motor-regulator-arm assembly comes with an adapter cable (pictured below the assembly in the above photo) that you will need to replace the old adapter cable.

Unscrew and remove three nuts on three screws holding the old motor-regulator-arm assembly in the door. On a BMW we used an 8 mm hex head to unscrew them.

Photo 3-2

There is a screw holding onto the window pane. To loosen the window screw to replace the old assembly, pull up the window until the lower edge of the window is exposed. (You should be careful, but on a BMW, manually pulling the window up and down is mellow, and the window is still supported by something internal. There's little risk of dropping and crashing the window, so have confidence.)

You're going to want to get the window screw lined up (vertically) in the hole in the vertical metal rail, as it is in the photos above and below. The window screw (above the red bar) needs to be loosened to remove the old motor-regulator arm assembly. On a BMW we used an 8 mm hex head to unscrew it. It's on quite tight. Have confidence. You have to push hard and turn to unscrew it. (But remember, there's glass under the screw, so stay in control.)

Photo 3-3

A closer view of the window screw (above red bar) to be removed.

Once the window screw is removed, pull the window up, and take out the old motor-regulator-arm assembly.

Put a protective face mask on and spray the moving parts of the new regulator-arm with lithium grease.

Replace the old assembly with the new motor-regulator-arm assembly. The new assembly comes with its own three screws and nuts, needed to screw it into the door. Loosen the window screw when inserting the new assembly into place.

Push the window back down, and screw the window screw back in. Now your new motor-regulator is in place.

Photo 3-4

Photo 3-5

Replace the old wire adapter, see the black plug with emerging colored wires in the two photos above, with the new adapter.

Photo 3-6

Plug the new adapter into the door wires, and attach it to the motor-regulator. You will be able to see how the two wires are supposed to line up with the metal motor-regulator prongs, based on the shape of the adapter.

Photo 3-7

Photo 3-8

Use electrical tape to tape errant wires to the door.

Snap back in place the wire bundles and door handle cable bundle that you snapped out.

Turn on the car engine, and roll the window up and down. It should work now!

4) Door panel reassembly (Takes 20 mn the first time):

Reattach the vapor barrier to the door by sticking it back onto the black gunk.

Smack the door panel back in, making sure it's firmly in the door.

Photo 4-1

Photo 4-2

Screw the door panel screws back in. Place a tiny piece of two-sided tape over each screw head before you put the screwdriver into the screws. This will keep you from losing the screws as you put them back in their holes. Screw them in.

Snap the plastic covers back over the screw holes they're meant to cover. For a long plastic strip with plastic nubs that fit into holes in the door, move the fitted end into place first, and then gradually press down along the strip, bending it a little to shove each plastic nub into its hole. Bang it in place with your fist.

Voila! C'est tout! Congratulations. The Earth and the beleaguered working/middle class will live to fight another day.

Possible small hitches, according to internet lore:

1)

You will have to unplug the air bags in the door, if your car has air bags in the door.

2)

If you ever need a temporary prop for your car window (for example, to keep up the window while you're waiting for your replacement motor-regulator assembly), you can use a couple of screws to stabilize into place a piece of window-propping wood that is 1" thick, 3" to 4" wide, and 10" to 15" long, inserted into the lower hole in the door visible in Photo 2-17 above. This is an odd size of scrap wood, so you might like to cut one (or have one cut on a slow day at the hardware store) and keep it around the garage for an emergency (if your car is about 10 years old, which is when automatic windows are designed to expire).

3)

According to the internet, there are many, fussier ways to fix a busted power window mechanism (involving McGuyvering individual parts within the motor-regulator-arm). If you were to pursue such a Mad Max approach, then you would be mechanically-inclined and possibly mechanically-experienced, and you should look for directions elsewhere on the internet, where they advise that some makes, models and years may or may not have rivets in the door panel, rather than screws. (Rivets may be internet myth. Internet experts said my car door was riveted together, but it was just screwed.) 

If there are rivets, and this is not just a mechanics' scare tactic, you'll just recall how quick and easy it is to take off the door panel, and you'll buy some dremmel disc blades (they're cheap) and use your dremmel tool to saw off the rivet heads. Then you use a small pick and hammer to knock the rivet bodies through their hole. Catch and keep the rivet bodies to size replacement screws (You can also try to find the proper replacement screw sizes on the internet). After you fix the window, replace removed rivets with hex-head machine screws (eg. M6X10) and locking nuts.

4)

On the BMW, internet trolls warn that you may need to "reprogram" the car to use all the fancy, no-hands power lock features from the driver's seat controls. This is simple. Turn the car ignition key to the ON position. Hold the window button down all the way. Hold the window button up all the way. Count to 10. Let the button go. Sounds like voodoo to me, and I haven't done this step yet, but the internet says it's so, so...

Update 1 year later: This piece of internet lore seemed to be pure BS, at least for my model and year. No reprogramming was needed.