The dome light in the back of our 2004 Toyota Sienna began coming on randomly when we’d be driving down the road. Also, when we’d try locking the doors with the keychain remotes we would get the “tone” telling us a door was open. And, most recently, our alarm would go off randomly when it was locked and parked. I figured it must have something to do with a switch on one of the doors and thought it was one of the sliding doors after re-shutting all of them when it wouldn’t lock with the remote. I’ve now replaced the switches on both side doors so some of the pictures will be of the left side and some will be from the right.
How to Fix Sienna Dome Lights Randomly Coming On And Alarm Going Off
Hardware:
- 2004 Toyota Sienna XLE
- Sliding Door Dome Light Switch, Part Number: 8423108030, Technically Called: Switch Assembly, Courtesy Lamp (For Rear Door). There is one on each sliding door and they are exactly alike. Get the part here: OEM Toyota part 84231-08030 Courtesy Lamp Switch
Tools Required:
- 10mm socket and ratchet (Get this and pretty much all the tools you’ll need for most common repairs in this Highly rated 170-Piece Tool Set
)
Step 1: Remove the 10mm bolt from the courtesy lamp switch assembly on one of the sliding doors.
They are on the body of the van at the back edge of the sliding door location and here’s it’s location:
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| Location of courtesy light switch for the left sliding door |
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| Bolt removed and the switch hanging out |
A closer look at the installed switch:
Step 2: Check the wiring connector and condition of the switch.
When I checked the first one everything looked ok. When I checked the other one I immediately noticed that it was soaking wet–bingo, the problem.
Step 3: Secure the wiring and remove the switch.
There isn’t much slack in the wiring running to the switch so be careful not to drop it back into the body because you’ll be taking off plastic panels on the inside of your fan if you do and you don’t want to add that to your repair process. I wrapped a bunch of electrical tape around the wiring connector and wire while I had the switch off. There is a little push button on the wire side of the connector that you push down and then you can pull out the connector. Be careful not to pull on the wire.
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| Electrical tape keeping the connector from falling back into the body of the van |
One thing I noticed when I was re-connecting the new switch(es) is that when the switch is bad the dome lights don’t switch on and off rapidly when you are loosening the bolt to the switch. The metal tab of the switch actually connects the switch to the body electrically and if the switch is bad it won’t be “switching” the switch when you are making and not making contact with the body (and the switch button is not depressed–meaning it is in the on position). When I put the new switch in the lights would go on and off rapidly. If you don’t want this to happen you can turn off the dome lights just to the left of the AC controls on the dash:
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| Dome light switch located just to the left of the AC controls on the dash |
Other Note: Be careful how you leave the connector if you are going to shut the sliding door because it might be possible that the door will smash the connector when it closes. You should probably be ok but you might think about that.
Step 4: Dry out the switch.
You can take the rubber grommet off the switch to aid in drying out the switch. I used a hair dryer.
UPDATE: after reinstalling the switch I still ran into problems. I then took the switch apart to see what was going on. It turns out that it was so corroded that one of the contacts that make the connection when the switch button was complete corroded off:
I tried to clean it up but then realized that both sides are critical. One side makes the connection with the wire running to the switch and the other side connects to the body whenever the button is pushed all the way in. If one’s missing then you have no switch. I purchased an after-market part from www.rockauto.com and you can see the pictures of the replacement part here. The manual’s testing procedure is as follows:
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| Courtesy Lamp Switch Testing Procedure |
Step 5: Reinstall the switch.
Again, be careful not to loose your wire! Now that I realized that the switch was bad because one of the contacts inside had broken off I’ll add that when you re-install a working switch you may want to hold the switch’s button in as you tighten the switch’s bolt because if you don’t, the switch will activate and inactivate your dome lights (and whatever other things like your van’s computer that gets the message that your door is open/closed) as the bolt makes good contact with the body and completes the circuit with the metal body of the switch.
Old Comments:
I’m now waiting to see if it fixed our problem but I’m pretty sure I found the issue. I used some ductwork tape to try sealing the switch better and I tightened down the bolt quite a bit to try to keep the water out of there. It must be coming from the outside, I hope it is otherwise I have a different problem.
This is what it looked like when I was done trying to seal it with tape:
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Hi John,
It seems I’m having a similar symptom now. Can I ask you that when this happened to your Sienna, does the display in front of the wheel show a door is opened/unlocked? For my Sienna, it doesn’t show any door is opened/unlocked, but only the dome lights are on, which is weird.
Thanks,
Gerry
Thanks – You made my day ! I was having this problem and expecting it to be difficult to find a solution online. You nailed it – and with awesome detail.
Glad you were able to fix your van!
Thank you for sharing so much information! I replaced all my Toyota Sienna bulbs with ease based on your instructions and the LEDs are a big improvement over the incandescent bulbs.
As for the sliding door switch issue, Before I ordered replacements, I removed them, sprayed them with a little TV tuner cleaner around the space where the plunger goes in and pressed it a bunch of times, also spraying while the plunger was fully depressed.. Voila! After over a month, they are still working perfectly. If the switch is corroded from water like yours was, this won’t help but it solved my problem without having to order parts. You could even do this with just removing the rubber cover.