What I learned fixing my front door lock (1 Viewer)

Joined
Sep 20, 2019
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76
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Colorado
Hi all,

I took a lot of photos and tried a lot of different things as I fixed the front door lock actuator on my 1997 LX450. I had bought the rig with it broken, so I can't say for sure when it quit. These assemblies are NLA and costly on eBay. Tearing the thing down and replacing the motor is the way to go. Here's what I learned.

I used this thread for research. I also used this one. That lead me to buying these motors from Amazon.

I extracted the lock actuator from the LX by following this video. Even though this clip is for the rear door, the process is essentially the same for the front. I didn't take a ton of pictures during this part, but if someone is really struggling with this let me know and I can pop the door apart and shoot some photos.

I took all of these photos with my phone camera to use as a reference when putting it back together.

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To start disassembly, pop this linkage off and make note of its orientation.

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Joined
Sep 20, 2019
Messages
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Next step in disassembly is removing this... position sensor? Is it a switch? Magnets, how do they work?

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Make note of how the arm on the thingamajig is aligned.

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Flip it over and remove the three large Phillips head screws that hold on the striker plate. I have no idea why I didn't take more pictures of this part, but it's straightforward. Gennnntly pry it off....

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The engineering on these is actually quite clever, the plastic is molded to pinch the springs in place. There's also a section that narrows, allowing for easier re-assembly. Well done, Aisin.

Here's how it all looks with the plate removed.

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Start removing components and placing them somewhere out of harm's way. Hunting for small pieces on the floor isn't fun. The small Phillips head screw needs to come out, too.

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Joined
Sep 20, 2019
Messages
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Colorado
Flip it over, remove all the screws from the top. It will take some force to pop the clamshell apart. Gently pry around the edges until it loosens up.

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Here's the guts.

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Gears looks fine.

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I de-soldered the wires and bench tested the old motor vs. a brand new one with a 12v tool battery. The original was TOAST.

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I pulled the worm gear with a small pry bar then pulled the motor apart for an autopsy.

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In hindsight, I probably could have just cleaned this up and put it back to work. the brushes looked like they had some life left in them. But I had the new motors already, so it was time to install one.
 
Joined
Sep 20, 2019
Messages
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Location
Colorado
I cannot stress enough this is what I learned. Sometimes failure is part of the process. Mistakes were made.

The old motor had ridges in order to have the gear be a press-fit. The new motors had a flat, so the gear spun freely. Also, look at how the body of the motor lacks soldering tabs. Ugh. At least I have 4 to ruin.

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I don't know what compelled me to try to use GLUE.

I cleaned it off and tried to braze on a threaded collar in order to clamp on to the flat. I picked these up for cheap at a local hobby shop.

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I did a test fit aaaaand the setscrew protruded far enough that it hit the clamshell. No bueno.

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Last resort: Brazing.

I roughed up the surface of the motor shaft, got some 60/40 rosin core and a propane torch and gave it a shot. That didn't work either.

At this point I was frustrated and gave up on the new motors. I figured other 90's Toyotas must have the same door lock parts, so off to the pick-n-pull I went.
 
Joined
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Messages
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Colorado
My strategy was to find cars of the same era, buy some motors, and see which ones worked.

The first vehicle I pulled an actuator from was a 1997 ES 300:

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Here's how that motor wound up looking: Same thread pitch, different motor and gear. Same clearance issue as the threaded collar. Skip these cars.

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Joined
Sep 20, 2019
Messages
76
Location
Colorado
I found a 3rd Gen 4 Runner with a door already dismantled, so I checked that out next.

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Bingo. This one is also from the front passenger side. I checked it with the baby-uggadugga battery and some scrap wire before purchasing.

Here's the motor while still in the 4-Runner assembly:

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Test fit the motor, deemed it acceptable, and wired it up.

DO NOT WIRE THE MOTOR UP AS SEEN IN THIS PHOTO. DO NOT SKIP POST THREE. DO NOT COLLECT TWO HUNDRED DOLLARS.

THE NEGATIVE SHOULD BE ON TOP.

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At this point, assembly is the reverse of disassembly. Apply new grease to everything, I used general purpose automotive grease.

Thanks for reading! 🍻
 
Joined
Feb 4, 2015
Messages
2,468
Very nice write up, but if i remember right, brand new small replacement motors for these switches are available/sold on Amazon and EBay. Even though this is hind sight you still may find the below thread a good read.
 
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Joined
Sep 15, 2016
Messages
673
Location
Chattanooga, TN
Another option for installing the gear on the new motors, which I've used 4 times successfully now, is to deform the motor shaft so that the gear is hard to slide onto the new motor shaft. Basically I took some large vice grips and smushed the middle area of the motor shaft, where the gear is to be installed on the new motors. Keep smushing them, even alternating orientation of the vice grips 180 degrees if the shaft starts to point to one side, until you can't slide the gear on by hand. Then you can lightly heat the gear and drive it on which should result in a well affixed gear if you spread the shaft enough. If the gear goes on too easily then pop it back off and further flatten the new motor shaft. If in doubt flatten the motor shaft a bit more because I had two of these slip after a few weeks of use and had to pull them and improve the tightness of the gear on the shaft.

I've been running all 4 door locks with these modded new motors for over a year of daily driving with no issues. I'd guess that you'll get more life out of the new motors than you will from most used motors.
 

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