Cheap Toyota Sienna Power Seat Fix – Sukkit Toyota

By January 23, 2013automotive, Tutorials


I noticed that the power seat started slipping in our 2004 Toyota Sienna.  I figured it was either something on the track, the motor, or some kind of gear.  What I thought would be a pretty easy fix turned into a total fiasco.

First, I have to put the disclaimer: This post is simply my fix for this problem.  I do not take responsibility for any damage to you or your vehicle which you may incur trying to mimic my fix.  I am not a mechanic.  You should consult a mechanic before attempting any work on your vehicle.

Also, if this helps you, please consider buying the items needed for the fix through my amazon link.  This gives a small percentage to me as a thank you!  Here are the materials:

JB Kwik Weld:

JB Kwik Weld

$6 and also great if you have Amazon Prime as you get free, 2 day shipping.  If you haven’t considered Amazon Prime, it’s a pretty sweet deal.  I use it.

Tekton Drill Socket Adapter Set:

Drill Socket Adapters

Again, $4 – and with Amazon Prime.  Pretty sweet!

Okay, enough about materials.

So, I’m a pretty handy guy.  I really love fixing things.  So, when the power seat starting acting up, I took a look.  So, at first, I simply started moving the seat back and forth, looking underneath.  Well, after that, the seat really started to get hosed.  Now the seat wanted to move sideways.  After a few more tries, the left seat track wouldn’t even move.  Great, so much for being handy!

So, to figure out what was going on, I decided to take the seat out.  I was pleasantly surprised that it only took 4 14mm bolts and it was out.  Well, I also had to disconnect the wire harness, but that wasn’t bad.  It took me a little while to figure out how it all worked, but now I know.

Basically, there is a motor in the front of the seat, behind some plastic molding.  That motor has two flexible metal drives inside plastic housing that looks like cheap pvc.  Those metal, flexible drives go into two gear boxes on either track.  Inside the gear boxes (black housing) are a worm gear (I’ll have a picture below) and a plastic helical gear.  This white, plastic helical gear is mounted on a threaded rod that goes inside the seat track.  This threaded rod has a metal block on it that is attached to a hex nut.  This is actually what moves.  If that is confusing, don’t worry, I have pictures below.

The problem on mine was the white plastic, helical gear inside the gear box in the front of the seat track.  Now, what’s absolutely ridiculous is that you cannot buy that part.  Nope, you have to buy the entire seat assembly for, wait for it………………………….$1700.  Yep, you read that right.  That really pissed me off.  After searching forever, I had arrived at the conclusion that there was no part replacement for my problem.  Yes, I could try to find a sienna left front power seat at a salvage yard.  But, after searching for a while, I wasn’t having much luck on that end either.

That’s when I came up with an idea.  That was to grind a phillips slot on the end of that drive shaft.  I figured this would solve my problem and so I enlisted my great neighbor, Joe, for his help.  Joe took a look, and then took it to his workshop.  A few minutes later he told me to come over and said he had a better solution.  He then showed me that if i slipped a 12mm 1/2 inch drive socket over the end that it was a great fit.  What a great idea!  He told me where to go so I could get it welded onto the drive.  I also needed to go get an adapter so I could hook a 1/2 inch drive 12mm socket to my drill.  I easily found this for, wait for it, $4 at Home Depot.  Btw, if you do JB Weld on it, this whole job should cost you around $10.

To make sure your problem is actually the gear, I have ordered the dis assembly so we can test the motor first

So, without further ado, here is my Sukkit Toyota Power Seat Gear Fix, complete with pics:

First things first.  Remove the seat behind the front seat you will be working on.  You will need to do this because you will lean the front seat back to remove the wiring harness.  Next, onto the front seat.  Start by removing the seat by removing the (4) 14mm bolts.  You may need to use an extension for the socket if the seat is moved waaaay forward.  I’m showing it with the seat removed for easy viewing.


Next, you will want to remove the wiring harness.  To do this, lean the front seat back.  Now, there are some plastic braces that keep the wiring harness from being loose.  Those are a pain to get off.  I broke a few of mine.  Oh well.  Once you get the braces off, it’s time to disconnect the wiring harness from the seat.  You may have to use a screwdriver to depress the connectors.  They were on pretty tight.

So, now you should have the seat free.  I moved it back out the big, sliding side door.  This made it easy to get out.  Once out, you will need to turn it over.  I used the back seat, in the compacted position, as a stand.  Simply put the front seat, upside down, on top of that.  It actually works out very nicely.  Now that you have that turned over, you will need to remove the front, plastic housing.  Unfortunately, I forgot to take pictures of this part.  There are two screws and four plastic “hooks”  on the sides.  Unscrew the screws and use a thin screwdriver to unhinge those plastic things.  Yes, this part is a little bit of a pain too.

Now, you will want to unscrew the side, plastic piece that hides the side of the seat track.  It has two screws, located here:


Sorry, I guess I didn’t frame that picture just right, but you get the idea.

I will now show you how to test the motor quickly to determine if that is your issue.  If neither sides of your track work, then this is most likely your issue.  If only one side works (ie, your seat starts to move sideways when you use the power seat button), then you will probably have to move further down after this part.

Here is a picture showing the bolts you need to loosen so you can get the flexible, metal shaft assembly out that goes from the motor to the gear housing on the seat track.  You can see the white, plastic housing that encases that flexible metal drive on the far, lower right.  There are one of these on each side that connect to a gear box on each side.  You need to loosen the screws so you can get those white, plastic things out.  You can even just remove the motor if it’s easier.


Here is a pic showing the whole flexible drive assembly.


Okay, now that it is out, you can test the motor.  To do this, you need to move the seat back to the van and hook the wiring harness back up.  Get a flashlight and shine it in the motor end and hit the power seat adjuster.  The motor is pretty powerful, so hang on to it pretty hard.  You should notice both ends move.  If you are having trouble seeing, put the flexible drive assembly back in one side at a time and test.  This will tell you if the motor is working correctly on both sides.  Now, just to be sure, hook up the flexible drive assembly to each side – one at a time.  Notice if the seat track moves on that side.  If the gear is stripped, you will notice that it may move a bit and then it stops.  This should help you deduce what is going wrong.  Obviously, if the motor doesn’t even work, then the problem is the motor.  You can actually find those online – so that may be a good thing.  But they are pricey.

Now, if one track is moving, but the other is not, then it is most likely the plastic gear in the gear box.  This next part shows you how to open that up and remove a key piece – if you want to try my hack with the drill!


Sorry for the horrible pic.  This is looking down on the bottom of the seat in question.  The red circle is a hex nut that has lock tite on it.  This makes it tough to budge.  You will need a hex driver, like pictured, and a sled hammer to move it.  A hammer may move it too, but the sledge is very persuasive.  Once that comes out, you can slowly slide the bottom seat track out the back of the seat.  This will expose the threaded drive that contains the gear.

Now you can see the threaded drive clearly.  Now, the silver block in the middle is what actually moves on the threaded drive.  This will have a black washer that needs to go back on top of it when you put the track back on and also the hex nut.  The circle on the left is showing the actual gear box that we will open.  It has two metal washers that can be forced off of it, when the time comes.



But first, we need to force a drive pin out of the assembly to actually remove the threaded drive – the big, silver, threaded bar.  Now, I am going to show you two pics because I want you to understand how this part works.  Basically, there is metal pin that goes through the seat track and the gear box to hold it all in the track.  The first pic shows you before I am putting it back in – I just want you to see what it looks like when you get it out of the track.  The second pic shows you how I actually drove it out.


Okay, now you know what it will look like when you get it out.  To actually get it out, you need a screwdriver that is big enough to drive it out, but not too big that will get stuck on the track it is housed in.  That’s because you will have to push the screwdriver through the entire housing as it’s fickle about coming out.  I used the sledge hammer again to coax it out.


Okay, now that it is out, you can tilt the thread drive rod down and pull it out.  Make sure you have the little, plastic piece out that fits over where the flexible drive shaft enters the gear box from the power seat motor.  If you do, it should pivot down and out of the track, like this:Toyota-Sienna-Gear-Box-Washers

This is the gear box.  You need to use a screwdriver to move those washers away from the black housing.  Once you do, you will be able to move the box open from using a screwdriver at the seam.  It’s very easy to open at this point.  Open it slowly to avoid losing any pieces.  Inside, if the gear is stripped, you will be met with this, like I was:


It’s pretty plain to see the stripped helical gear.  You cannot buy this piece of the threaded drive that it is housed on.  So, what I did is remove the metal worm gear on the left.  This ensures that it is easy to move the threaded drive around with a drill at the end.  This is the worm gear you will be removing:


Okay, before we reassemble everything, we want to attach a 12mm socket to the back of the threaded drive.  If you want to make sure this never comes off – have a metal shop weld it on for you.  Now, and this is very important.  They will need to weld it to the back of the drive, attaching it to the washer like feature at the back.  They have to weld both sides of that washer – first the 12mm 1/2 inch drive socket and then the actual washer thing to the threaded drive as it is not fixed to it.  Or you will end up with a socket that spins the washer at the back of the threaded drive like I did.  This is where you will affix the 12mm socket:


Note: the gear box is on the opposite side, toward my hand in this pic.  The socket should be welded (again – make sure the socket side and the threaded shaft side is welded to the metal washer type thing on the end.  This is the end that will point back,  toward the back of the van when you reinstall it.

Now, once you have that welded, it’s time to reinstall everything.  It should be noted that you can use JB Quik Weld on this.  Doesn’t take much time.  You just need to use on both sides of the washer thing.

Put everything back in reverse order and you are ready to test.  Make sure if you use JB Quik Weld to let it cure enough before testing.  Here is pic of me after my test with my drill.  Just match the power seat speed with the appropriate drill setting and you’re ready to rock!


Just a note that you will probably need an attachment to lengthen your 1/2 inch socket so you can reach the seat drive in the seat track.

Now, sit back and tell Toyota to sukkit!



Related Posts: