Buzzing sound rear of vehicle.

[Falls]

Today I go out in the garage to do some things , truck has been sitting for about 5 hours and was not running . All was quiet , then I notice this buzzing sound coming from the rear of the truck. I was not able to crawl underneath it to pinpoint its exact location & never heard it before. It sounded like a pump of some sort , like would be for air leveling or something like that . Maybe lasted 5 min. or so then stopped.

Any thoughts

 

[Uneek]

It's probably the emissions or evap system that purges after five to six hours after you shut off the engine.

 

[Falls]

It's probably the emissions or evap system that purges after five to six hours after you shut off the engine.

Thanks for the info , didn't even know that happened and after 2+ years I never heard it before . I'll listen for it again to see if I can pin point the area if I ever hear it again.

 

[toto]

Uneek is correct. It's a pressure test by the EVAP system that was added to many 2006 Toyota models. See the attached PDF.