Strange noise coming from the back of my GX
 

The other morning I went out to the garage and heard a strange noise coming from the rear (underneath the 3rd row seating/storage area) of my GX460. It sounded like a pump or something running continuously. I was in the garage for 10 minutes and the noise had started before I entered the garage and continued after I left. When I went back out to the garage 3-4 hours later it had stopped so I am not certain how long it was running for. I previously owned a 2006 GX470 with the rear air suspension and this was not the sound that was coming from my new GX. The car had not been running or driven in over 8 hours and I am at a loss as to what it could be. I figured I would check here first before delving into the 700+ page owners manual to troubleshoot.

Any thoughts/ideas/suggestions would be greatly appreciated.

Check to see if your third row seats are all the way down.

Koz

There is a note about this noise in the owners manual but I do not recall the details except that it said something about a noise may be heard from the rear of the vehicle a few hours after the car has been driven and that it was normal. I have only heard it once probably 3-4 hours after it was driven.

To clarify, the noise is coming from underneath the car...it is not the 3rd row seat.

As CdeFabio stated or if you have rear air susp it can make noise after the vehicle is turned off and you have exited.

Koz

I think it's your air suspension. Mine did that once and I pushed up and down on the rear bumper and it stopped.

sanidel has the right answer. It happens in other toyotas too. My GX does it and I don't have the air suspension.

It is quite noticeable though.

it's the vacuum pump to the charcoal canister. your car has a "key off" evap system. the noise will last longer when you have less fuel in the tank.

Thanks for this, I have encountered this twice in the morning (in the span of about a week) when I am going out to the car to leave for the day. I was concerned it was something that had been running all night and a possible drain on the battery. I'm going to keep an eye ( . . . ear) on this and see what happens, but this post will help me sleep better-- KH