[dphflytyer]

When I start my runner and nothing else is on radio,fan I keep hearing a noise like a clicking sound coming from behind the dash by the passenger air bag. It sounds like a motor or gear trying to engage and slipping. Same noise if its hot or cold inside. Anybody else had this happen and is it something to be concerned about. Thanks

[shootmymime]

do you have the limited climate control? could it just be the doors / HVAC moving around?

[Doc2012]

Your air bags don't have any kind of fan or anything in them. No moving parts.

Basically, think of your air bag as a 12g CO2 canister attached to a bag at the nozzle. A nail punctures that canister, and fills the bag up with air, then it slowly leaks out.

NOT saying that's how airbags work, but it's kinda the same concept.

If its coming from behind the dash, look at your blower fan. Or, like someone suggested, possibly your climate control trying to close the doors if you have a limited.

[ecliptic]

I have the same noise in my 2008 Highlander. Furthermore, when I get out and walk around and sit in the passenger seat, it immediately stops. It's definitely something to do with the passenger air bag. If you find out what it is, please let me know.

[dphflytyer]

Exactly, as soon as I sit in the passenger seat it stops. Gonna try and figure it out this weekend.

[Doc2012]

Ok.

Again, there are NO fans in air bags. That would be a HORRIBLE idea.

Plus, there isn't a fan small enough that could inflate the airbad in the micro seconds that it takes.

Air Bags are inflated by a chemical reaction. Here ya go:

How an Airbag works - YouTube


Sounds like a gear?

What about the gears that are under the seat that move the seat? What about the inflater for the back support? What about the sensor in the seat that is triggered when some sits in the seat, alerting the airbag and sealt belt light there is weight in the front seat?

Take the four bolts out that hold the seat to the floor board. Lean the seat back. Listen to under the seat. Look and see if there's anything moving that shouldn't be.

[ecliptic]

Doc2012 - The noise is not in the seat.

Alright, I made some progress today on the clicking noise. I discovered when I turned the A/C temperature dial from cold to hot, the noise stopped. So then I searched on the web and found this discussion on another Toyota board: Clicking noise under dash and stuck HVAC control arms/ blend doors on Limited

Since the noise in my Highlander started after a day when I had to use both the cooling and heating on the same day (same as the guy with the problem on this other board), I think I may have a blend door servo motor going out. Why the noise would stop when I sit in the passenger seat is beyond me (see my previous post). Hope this helps someone.