Everytime I hit a bump whether big or small I hear this annoying, squeaking sound from the back. I thought it may be the spare tire underneath but I tightened that up and I still hear that sound.

Do I have something loose back there? or is there some other explanation for that noise?

 

I get that noise when I have a passenger in the rear seat wearin a seat belt. It squeaks constantly. Annoyingest thing ever, cant really tell em to unbuckle the seatbelt on the freeway . . . don't want to risk getttin a ticket

 

My reciever hitch was toughing my rear bumper and when i hit a bump it would squek .

 

I am guessing that in the suspension area, something is not properly lubricated? Just my thoughts! :fireman:

 

Thanks for the suggestions...I hope I can fix it...'cos damn that thing is annoying!!!!

And I know it's coming...but it annoys me anyway...

 

My 2002 4runner also had same noise.
I suspected It came from the Hinges or Latches of the rear back seat, I wil try to see I can lubricate them.

 

Mice, definitely mice! :confused:

 

Try unlatching the rear seatbacks to see if there's any effect. I've had 'em squeak.

 

Your '99 may be a little too new for this problem, but if all else fails check the bodymount bushings.