How to Fix Moisture in Headlight-Toyota Sienna

Moisture in Toyota Sienna Headlight
How to Fix Moisture in Toyota Sienna Headlight

This article shows you how to fix moisture in headlight of a 2004-2010 Toyota Sienna.  When we arrived back from an all day trip where it rained the entire time there was moisture in our passenger side headlight of our 2004 Toyota Sienna.  I did some research and it turns out that there was a manufacturing defect on the right side headlight and the seam fails and water leaks into the headlight.  Time for another repair.  I wasn’t sure how this was going to go but I’m very pleased with how the repair turned out so follow along if you want to know how to Fix Moisture in Headlight of your Toyota Sienna.  The major reason for repairing the one headlight instead of replacing it, is that if you replace one headlight you’ll have two different looking headlights–one with a yellow tint and a clear one.  I’d rather repair it if possible and it’s very possible and I’ll show you how…

How to Fix Moisture in Headlight-Toyota Sienna


Parts Needed:

Tools Needed:

Step 1: Pop the hood.

The hood release is by your left knee when you are sitting in the driver’s seat.  Release the safety latch, lift the hood, and put the hood rod in place to hold it up.

Step 2: Disconnect the four electrical connectors to the bulbs.

There are four connectors on each headlight (low beam, high beam, turn signal, and a side bulb too)

Toyota Sienna Headlight Lightbulb Connector Locations
Toyota Sienna Headlight Lightbulb Connector Locations

Here are the outside three connectors:

Toyota Sienna Outer Headlight Bulb Connectors
Disconnect the electrical connectors

Here’s the inside connector:

Toyota Sienna Inner Headlight Bulb Connector
Headlight bulb electrical connector instructions

Step 3: Remove the top headlight screws.

Remove the top two phillips-head screws from the headlight frame:

Toyota Sienna Top Headlight Screw Locations
Toyota Sienna Top Headlight Screw Locations

Step 4: Remove the left two grill clips.

There is one headlight mounting screw that is hidden under the grill so you need to pop out the left two clips from the grill.

Toyota Sienna Left Grill Clips Locations
Pop out the two left clips

Pop up the centers and then pry out the clips.  This is what they look like removed:

Sienna Grill Clip Removed
Grill Clip Removed

Step 5: Pry up the corner of the grill and locate the inner headlight mounting screw.

Grip the grill as seen below and carefully pry it toward the front of the van to expose the inner headlight mounting screw.

Pry the corner of the grill like this
Pry the corner of the grill like this

Remove the screw seen below.  Be careful to not drop it down in the bumper or you may create more work for you.

Remove this inner headlight mounting screw
Remove this inner headlight mounting screw

Step 6: Pop out the center of the front two wheel well clips.

Here is the location of the two clips we need to remove.  We are only removing the pin from the inside of it.

Pop the centers out of these two clips
Pop the centers out of these two clips

Pry up the inside pin and then pull out completely.  The rest of the clip will stay in place as the bumper just slides into it from the side.

Pry the center pin of the clip out
Pry the center pin of the clip out

This is what the pin looks like when it is removed:

Fender clip pin removed
Fender clip pin removed

Step 7: Unsnap the bumper from the quarter panel.

The bumper snaps to the quarter panel with three clips along its seam.  Here is a video of me releasing these clips:

I have written a detailed step-by-step tutorial on how to completely remove the bumper for my article on how to replace the radiator.  You don’t need to remove the entire bumper but you can refer to Step 9 on the page linked above.

Step 8: Pop the edge of the fender free.

For both of the clips where you removed the center pins pry the bumper out of the clips as shown below:

Toyota Sienna Prying the Bumper From Fender Clip
Lift the clip with your thumb while prying the bumper out

Once you have released the two clips the bumper will open up:

Toyota Sienna Bumper Disconnected from Quarter Panel
Toyota Sienna Bumper Disconnected from Quarter Panel

Step 9: Remove the outside headlight mounting bolt.

You will now be able to access the outside mounting bolt as shown here:

Toyota Sienna Outside Headlight Mounting Bolt
Location of outside mounting bolt

Use a 10mm socket and ratchet to remove this bolt:

Toyota Sienna Removing Outside Headlight Mounting Bolt
Using a 10mm socket to remove the outside bolt

Step 10: Remove the headlamp assembly.

I first lifted the top two brackets off the little post they were caught on:

Lift the bracket off the post
Lift the bracket off the post
Lift the bracket off the post it slips down on
Lift the bracket off the post it slips down on

You will then need to play around with working the headlight out of the vehicle.  Pry up on the grill like you did when you removed the front screw in Step 5 and work the headlight out of the opening.  Here it is out:

Headlight freed from van
It’s out finally
Headlight removed
Headlight has been removed, now time to fix it

Step 11: Remove all the bulb assemblies from the headlight.

Back Side of Toyota Sienna Headlight
Remove the four bulb assemblies from the headlight

Each of them turns about 30-degrees counter-clockwise and then pulls straight out to remove.  Remember not to touch the glass bulbs of the high and low beam bulbs or you will surely shorten their lifespan because of the oil on your fingertips.  The inner headlight bulb (high beam) has an orange rubber o-ring on it:

The inner headlight bulb removed
The inner headlight bulb removed

The outer headlight bulb (low beam) has a yellow o-ring on it:

The outer headlight bulb removed
The outer headlight bulb removed

The third from the inside will be the turn signal and that bulb is colored yellow.  The yellow plastic on the bulb was flaking off on mine and that may have been because of the moisture inside the headlamp:

The turn signal bulb--it needs replaced
The turn signal bulb–it needs replaced

The outside bulb is shown below and it was obvious that it was burnt out (and I didn’t even know there was such a bulb honestly):

Here's the outside light bulb assembly removed--it's burnt out
Here’s the outside light bulb assembly removed–it’s burnt out

Step 12: Dry out the inside of the headlight.

There was quite a bit of water on the inside of my headlight.  I first set up my “blue blower” and let it blow in the two outer bulb holes and let that run for a few hours:

Drying out Toyota Sienna Headlight
Using a blower fan on my headlight to dry it out

I then realized how much water was in the bottom of the headlight when I heard it slosh around in the bottom.  There was a lot of water in there:

Water Level In Toyota Sienna Headlight
Water Level In Headlight

When I saw how much water was in there I knew it would take forever to dry out with just air.  I also knew the openings where the lightbulbs go in are not shaped to easily pour out water (so I could now just pour out the water) so I decided to drill a 1/4″ hole in the bottom of the headlamp (outside of where it would be visible) in order to pour the water out:

Location of Hole Drilled in Toyota Sienna Headlight
Location of hole drilled to drain water

This is how much water drained out:

Water Poured out of Toyota Sienna Headlight
This is all the water that poured out of my headlight


I used a hair dryer for a little while but never left it unattended and kept it on the lowest heat setting.  I didn’t leave it blowing in one hole for long and even with that, the plastic got pretty hot.  I taped a cardboard tube onto the hair dryer to put some space between the dryer and the headlight:

I tried using a hairdryer on low for a while
I tried using a hairdryer on low for a while

For the most part I only used the blower on the headlight to dry it out and once I drained the water out by drilling the hole it started drying faster.  It took at least 2-3 hours to dry out the headlight and there still were a few drops in there when I decided to move forwards anyway…

Step 13: Apply glue to the headlight seam.

At this point I was not too sure whether I would try re-sealing the headlight or I was just going to drill some holes in the bottom and leave it open for the water to drain out.  I decided I would try re-sealing it and see how it went and then I could either drill more holes in the bottom or seal it up.

I used the glue application syringes I have linked in the parts section at the top.  Take the plunger out and fill the syringe with glue, leaving a little room for the plunger as seen below:

Filling the syringe with adhesive
Squirt the adhesive into the syringe without the plunger in it

I tried the blue tip size but the glue would hardly come out of them.  I tried the next larger size, green, and it worked very nicely and the tip still did fit down into almost all the seams:

Green syringe
The green size worked best for thickness and flow

It required quite a bit of pressure on the plunger to keep the glue flowing but it worked nicely.  Flood the seam between the clear plastic and the black back plastic piece as seen below:

Flooding the Headlight Seam with Adhesive
Flooding the Headlight Seam with Adhesive

Put the tip of the syringe as deep into the seam as you can and let the seam “fill up” as you move the syringe along.  I liberally flooded each place where the snaps were to make sure it was sealed in those locations as seen below:

Flood the Snap Areas with Adhesive
Flood the Snap Areas with Adhesive
Inside seam
Inside seam
Outside Seam
Outside Seam
Top Seam
Top Seam
Toyota Headlight Seam Re-Sealed Bottom annotated
Bottom Seam

I didn’t worry about the bottom seam that much because gravity will pretty much keep the water from going in there but while I was working on it I went ahead and sealed the lower seam too.

Step 14: Allow the glue to set up.

This adhesive said it set up in 5-6 minutes but I had started applying it before all the water had been dried inside the headlight.  I put the blower back on the headlight to help the adhesive to cure and to dry the headlight out a bit more inside.

Step 15: Reinstall the bulbs.

First make sure to replace the burnt out bulbs if they were bad.  My headlight bulbs were good but the turn signal had the pealing plastic coating and the outside tiny one was definitely bad.  I replaced the tiny bulb (the far outside one) on the driver’s side of the as well since you get two bulbs in one pack and I figured it was bad (and I didn’t even know there was such a bulb in my van on the very corners).  One thing to note is which headlight bulb is which.  The orange o-ring bulb is the high beam bulb and the yellow o-ring bulb is the low beam bulb.  Here is how they went back in for me (orange o-ring on the left and yellow one on the right):

Toyota Sienna Headlight Bulb Assignments
Toyota Sienna Headlight Bulb Assignments

Don’t forget to put back in the turn signal light bulb and the tiny corner bulb too.

Step 16:  Seal up the drain hole you drilled.

At this point I decided that my adhesive was going to do a good job of re-sealing up the headlight and I wanted to fill the hole I had drilled in the bottom of the headlamp in Step 12.  I liberally squeezed some adhesive in the hole, put a piece of clear packing tape over the hole, and then reoriented the headlight so the hole was facing down so the adhesive did not run up into the headlight and let it rest (with the hole oriented down) for 10 minutes or so to set.

drain hole filled with glue
Fill the drain hole with glue and place tape over the hole

One thing to note–these headlights DO have “breathing holes” built into them and you can see one here with Styrofoam in it:

Location of headlight vent
Location of headlight vent

Step 17: Re-insert the headlight into the van.

It was a little tricky but you will need to carefully guide the headlight back into place.  I pulled back the grill a bit to give me some space.  Be careful not to apply to much force to any of the tabs that stick out of the headlight so you do not break something off.  I first got it partially in place as seen below:

Headlight partially in place
Headlight partially in place

One tight fit area is the V at the top where the mounting tab must be on one side of the quarter panel and the headlight on the other:

Guiding the headlight back into place
Carefully guide the headlight back into place

Step 18: Reinstall the headlight screws and bolt.

Do not over-tighten these screws as you could crack the plastic.  Pull back the edge of the grill and line up the mounting tab’s hole with where it screws in place:

Front Mounting tab
Pull back the grill to see the front mounting tab

I used my flexible claw pickup tool gripped on the head of the screw to get the screw started down in there:

Using my flexible grabber to start the screw
Using my flexible claw pickup tool to start the screw

Line up and reinstall the top mounting screw:

Top mounting tab screw location
Top mounting tab screw location

Reinstall the outside mounting bolt via the seam of the bumper:

Outside mounting bolt location
Outside mounting bolt location

Step 19: Snap the bumper back together.

First I made sure the wheel well clips were lined up correctly.  If you do not get it all lined back up correctly you may end up having to unsnap the bumper again and you don’t want to have to do that.  You’ll want to make sure the black plastic wheel well lining is tucked behind the edge of the bumper.  The white wheel well clips need to wrap the edge of the bumper as seen below:


Line up the bumper and the wheel well clips
Line up the bumper and the wheel well clips

Now align and snap the bumper seam back to the quarter panel.  This is what the seam of the bumper should look like when it is snapped back into place:

Bumper snapped back in place
Bumper snapped back in place

Step 20: Reinstall the fender clip center pins.

This is what the clips should look like before reinstalling the center pins:

Wheel well clips ready for their pins
Wheel well clips ready for their pins

Reinstall  the two pins:

Reinstalling the wheel well clip center pins
Reinstalling the wheel well clip center pins

Step 21: Reinstall the grill clips.

Pop the centers out of the grill clips and insert them and press in their centers:

Reinstall the grill clips
Reinstall the grill clips

Step 22: Reconnect the electrical connectors to each headlight bulb.

Reconnect all four electrical connectors to their fixtures.  The bright headlight (inside bulb) is a black connector, the low-beam bulb is a brown connector, the turn signal bulb has a grey connector, and the small black connector goes to the outside bulb:

Headlight Electrical Connector Colors
Here’s the colors of the connectors and where they go

Step 23: Test out your headlights.

If you’ve done everything correctly your dim and bright headlights, your turn signal and your side lights should all work.  You’ve saved yourself probably $500 over having a dealer do this and you recycled a poorly manufactured headlamp and have given it a longer life.

All the bulbs are working
All the bulbs are working
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  • John Mueller, excellent job on this tutorial. If I were a teacher, I give it an “A” on this paper. Anyway, I also have a 2004 Sienna XLE model with the HID xenon bulb. It went out last week after couple days of November rain. The bulb is burnt. Lots of moisture inside the headlight assembly. Initially I thought I needed only to replace the bulb, but it’s a bigger problem than I thought. On models with the HID (high intensity discharged) assembly, there is a headlight ballast (control unit) sitting underneath the assembly that might also be bad. This unit needs to either be replaced (used from e-bay, ~$60) or cleaned, dried unit thoroughly. I am waiting for the ballast control unit from e-bay to arrive before I tackle this project. Thank you again for this excellent write-up.

    • Thanks for the feedback Jack. You’re the first to give me a grade–I always wanted to get A’s! The HID bulbs do complicate this repair and lucky for me I had the cheap headlights. Unfortunately for you, the HID version suffers from the same manufacturing defect. Please check back in and Share Your Repair and let other HID owners know how it went and if you have any tips for them.

    • John, I finally got my HID front passenger headlight working again thanks to your excellent tutorial. I ordered a used headlight ballast from e-bay (~$60) and replaced the corroded one. Put everything back together and voila! The ballast is just underneath the light assembly. Now, I need to tackle cleaning up the foggy outer lens of both headlamps.

      • Great to hear Jack, now it is all downhill from here–there’s tons of resources on polishing up your headlights. I recently watched one that I like, from a Youtube channel I just started following, ChrisFix, because he shows you how to keep them from turning yellow again, (as all mine have yellowed again after I polished them clear): ChrisFix, How to Restore Headlights Permanently The trick is to use a clear-coat paint after you polish them to keep them from oxidizing.

  • This is a fantastic repair article – Thank you Mr. Mueller!

    As a suggestion for marginally clouded headlight assemblies, I have used my halogen work lights as heating lamps to evaporate minor condensation very successfully.

    Starting at the base of the headlamp cover, slowly heat the entire cover and then continue to broadcast the heat on the specific regions of condensation. Use cardboard to shield the plastic headlamp cover to ensure you do not damage and overheat the cover. To correct the condensation took about 30 minutes.

    • Thank you for the feedback. I have a question–how do you get the water out of the headlight though? If you cause the water to evaporate within the lens, but do not replace that hot moist air, with cool dry air, will not the moisture condensate on the inside of the lens again when the lens cools? I found it difficult to circulate much air through my headlights because the openings are small.

    • The repair is holding up great–no water in it now after almost 5 months! If I run into problems I’ll definitely update the article with what happened and what I did to resolve it.

  • Nice writeup. But, you are lucky, you don’t have the Xenon HID lights. The HID bulb is $100 oem, you can get them less expensive…

    • Hmmm, I’m leaving a reply to my reply… This is an excellent writeup after I just went back and looked at it again. Really thorough and includes a nice list of mat’ls needed at the beginning. I do have the HID bulb . Not sure I have all the parts, going to try taking it apart now…


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