2010 Toyota 4Runner Owners Manual - Page 381
2010 Toyota 4Runner Manual
Page 381 highlights
3-2. Using the audio system Party mode switch You can switch the sounds quality types by pressing the switch. Base mode Party mode In party mode, the sound volume from the speakers on the back door is bigger than in base mode. (The output from the speakers on the rear doors will be transferred to the back door speakers.) 3 CTH32AS048